Elements of chemical philosophy

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ELEMENTS

OF

CHEMICAL PHILOSOPHY.

\

BY

SIR HUMPHRY DAVY, LL. D.

Sec. R. S. Prof. Chem. R. I. and B. A. M. R. I. F. R; S. E.
M.R. I. A. Member of the Royal Academy of Stockholm; of
the Imperial Med. and Chir. Academy of St. Petersburgh ; of
the American Philosophical Society ; and Honorary Member
of the Societies of Dublin, Manchester, the Physical Society of
Edinburgh, and the Medical Society of London.

BART I. VOL. L

LONDON:

PRINTED FOR J. JOHNSON AND CO. ST. PAUL's
CHUKCH-YARD.

1812,

London: printed by W. Bulnaer and Co. Ciev eland-row.

TO

LADY DAVY.

There is no individual to whom I can with
so much propriety or so much pleasure
dedicate this Work as to you. The interest
you have taken in the progress of it, has
been a constant motive for my exertions;
and it was begun and finished in a period
of my hfe which, owing to you, has been
the happiest. Regard it as a pledge that
I shall continue to pursue Science with
unabated ardour. Receive it as a proof
of my ardent affection, which must be
unalterable, for it is founded upon the
admiration of your moral and intellectual
qualities.

H. DAVY.

i

t

1

ADVERTISEMENT-

In this Work I have endeavoured as far as it
was in my power, to employ the nomencla-
ture most in use amongst the chemists of the
present day in Britain. In consequence of the
progress of discovery, some of the names
adopted from the French School of Chemistry
now imply erroneous ideas. In such cases I
have recurred as often as was possible to the
familiar names, or the old names.

In adopting new names, I have been guided
by the necessity of the case ; and have applied
them only to new substances, or to substances
the nature of which had been misunderstood,
and which were confounded with other bodies
differing from them in their nature.

I may perhaps be censured for having pro-
posed to signify the combinations of chlorine
or oxymuriatic gas by simple terminations, con-
nected with the name of the basis, such as ane
and ana ; but these terminations will serve at

vi

ADVERTISEMENT.

least as symbols of the class, and in this way
may assist the memory.

In the last Bakerian Lecture, published in the
Philosophical Transactions, I have proposed to
denominate the combinations of chlorine sup-
posed to contain one proportion, by the termi-
nation ane, those supposed to contain two by ana,
and those containing three by anee. As, how-
ever, amongst the metallic combinations of chlo-
rine, there are never more than two distinct com-
binations belonging to the same metal, I have
given the termination ane to the first, and that of
ana to the second, without reference to propor-
tions ; or where there has been only one, I have
used simply ane. If my original proposal
should be adopted, it will however be easy to
make the corrections, and the cases are very
few that will require it. Common salt, which
contains two proportions of chlorine, and
which in this work is called sodane, will be
called sodana ; ferrane will be called ferranea
ferranea, ferranee ; and arsenicane must be
chan2;ed to arsenicana.

Some persons may chuse rather to use the
word chloride, following the analogy of oxide ;
but as I have expressed in the Introduction, our
nomenclature would have been more simple and

DSI

ADVERTISEMENT. m

useful without any attempt at tlieoretkal ex-
pressions of the composition of bodies ; and
as the fixed alkalies, earths, and oxides, are
similar bodies, and the termination a has been
applied to the two first, it might be properly
extended to the last.

The word oxide is however now current, I
have therefore used it, and have employed Dr.
Thomson's method of distinguishing the dif-
ferent oxides of the same metal, by prefixing to
them syllables derived from the Greek nu-
merals ; deutoxide, tritoxide, tetroxide^ signify
that the bodies contain two, three, or four pro-
portions of oxygene. When the word oxide
alone is used, one proportion only of oxygene
is supposed to exist in it.

Whatever pains be taken, it will not be pos-
sible to make the existina; nomenclature con-
forrjaable to the idiom of our language ; and till
some general principles for its improvement
are agreed to by the enlightened in different
parts of Europe, it cannot be expected to be
even a philosophical language ; and till a more
simple system is adopted, innovation will be
censured sometimes perhaps even when it is
necessary, and Neology generally brought for-
ward as a reproach.

ADVERTISEMENT.

I have in a few instances only, given an ac-
count of the experiments, from the results of
which the numbers representing the undecom-
posed bodies were calculated.

To have given accurate histories of those
experiments, would have been incompatible
with the object of an elementary book devoted
to the 2;eneral truths and methods of the
science ; I shall however shortly present them
to the publick, in a work containing the details
of labours that I have carried on durina. the
last twelve years in analytical chemistry.

I have usually given whole numbers, taking
away or adding fractional parts, that they may
be more easily retained in the memory. When
the number was gained from experiments in
which a loss might be supposed, I have added
fractional parts, so as to make a whole number.
Thus the number representing barium,, is
nearer 129 than 130; but it is given as 130,
because it was deduced from an indirect ex-
periment in which a loss of weight was more
probable than an increase from any foreign
source.

In a future edition of this work, should
my imperfect labours be favourably received,
I may hope to be able to complete the

ADVERTISEMENT. ix

series of numbers, and to fix some that are
doubtful.

I cannot conclude without acknowledging
my obligations to my brother Mr. John Davy,
for the able assistance he afforded me in the
progress of the researches which form the
foundation of this treatise.

I have likewise received much useful expe-
rimental aid from Mr. E. Davy, and Mr. W.
Moore.

The greater number of the experiments
were made in the laboratory of the Royal
Institution ; and all that were fitted for demons-
tration have been exhibited in the Theatre of
that useful publick establishment in my annual
courses of lectures ; and have been received by
the members in a manner which I shall always
remember with gratitude.

BerTceley Square^
June 1, 1812.

CONTENTS

Introduction . . . page 1

Historical View of the Progress of Chemistry.

PART I.

ON THE LAWS OF CHEMICAL CHANGES: ON
UNDECOMPOUNDED BODIES AND THEIR PRI-
MARY COMBINATIONS . . 6l

DIVISION I.

ON THE POWERS AND PROPERTIES OF MAT-
TER, AND THE GENERAL LAWS OF CHEMICAL

CHANGES.

Preliminary Observations , , 63

Of the Forms of Matter . . 65

Gravitation . . • 67

Cohesion . . .63

Of Heat, or calorific Repulsion . 6Q

On chemical Attraction, and the Laws of Combination

and Decomposition . ; 98

Of Electrical Attraction and Kepulsion, and their

Relations to Chemical Changes . . 125

On Analysis and Synthesis: on the Circumstances
to be attended to in these Operations, and on the
Arrangement of undecompounded Bodies 180

CONTENTS,

DIVISION II.

OF RADIANT OR ETHEREAL MATTER.

Of the Effects of radiant Matter, in producing the

Phaenomena of Vision . page 195

Of the Operation of radiant Matter in producing

Heat ..... 201
Of the Effects of radiant Matter in producing chemical

Changes . ; . . 210

Of the Nature of the Motions or Affections of radiant

Matter . . . . 213

DIVISION III.

OFEMPYREALUNDECOMPOUNDED SUBSTANCES,
OR UNDECOMPOUNDED SUBSTANCES THAT
SUPPORT COMBUSTION, AND THEIR COMBIN-

ATION WITH EACH OTHER.

General Observations . . , 225

OfoxygeneGas . . . 227

Chlorine, or oxy muriatic Gas . . 235

DIVISION IV.

OF UNDECOMPOUNDED INFLAMMABLE OR
ACIDIFEROUS SUBSTANCES NOT METALLIC,
AND THEIR BINARY COMBINATIONS WITH
OXYGENE AND CHLORINE, OR WITH EACH

OTHER.

Preliminary Observations . . 245

Hydrogene Gas, or inflammable Air . 246

Of Azote, or nitrogene Gas . . 255

Of Sulphur . . .271

Of Phosphorus . . . 285

Of Carbon or Charcoal, and the Diamond 299

Of Boron, or the boracic Basis , , 314

CONTENTS.

DIVISION V.

OF METALS; THEIR PRIMARY COMBINATIONS
WITH OTHER UNDECOMPOSED BODIES, AND'
WITH EACH OTHER.

vrPnpral Ohsprvation<5

. page 319

Of Potassium

321

Sodium

S31

TJarium . . .

-L^uX J I.XX ( #9

338

Strontinm

. 343

Calcium

345

Maenesium

350

Aluminum .

354

\iliiriniirn

358

X^'s 1 V^vJ if U U.J « •

S60

Sill Oil in

362

T t Iriii m

X Lift lU ill « 4

364

fvl n ca npQn m

xvj CLii a Li^oU ill •

366

i^inc or Zinouni

373

Tin^ or Stannum .

370

Iron, or Ferrum . .

. . 384

TiPari nr T*lnmV>nm

3Q4.

Antimonv. or Antimonium

400

jjibinuiij^ or jjisnjuiiiiuiu

Tellurium

408

Cobalt, or Cobaltum

411

Copper J Cuprum

415

l^ickel, or Nickolum

420

Uranium . .

424

Osmium

. 426

Tungsten, or Tungstenum

427

Titanium

430

Columbium . .

431

Cerium . - .

. . 433

Palladium • .

434

xiv

CONTENTS^

Iridium . . . page 436

Rhodium . , 437

Mercury, or Mercurium • - 438

Silver, or Argentum . , . 443

Gold, or Aurum . . . 446

Platinum . . . 448

Arsenic, or Arsenicum . , 453

Molybdenum , . . 459

Chromium . . . 462

DIVISION VI.

OF SOME SUBSTANCES, THE NATURE OF WHICH
IS NOT YET CERTAINLY KNOWN.

Preliminary Observations . 465
Of the Fluoric Principle . . ih.
Of the Amalgam procured from ammoniacal Com-
pounds . . . . 473

DIVISION VII.

ON THE ANALOGIES BETWEEN THE UNDECOM-
POUNDED SUBSTANCES; SPECULATIONS RE-
SPECTING THEIR NATURE; ON THE MODES OF
SEPARATING THEM, AND ON THE RELATIONS
OF THEIR COMPOUNDS.

Of the Analogies between the undecom pounded Sub-
stances; Ideas respecting their nature . 478

Of the Analogies between the primary Compounds,
and on their chemical Relations . . 490

On the relative Attractions of the undecomposed
Substances for each other . . . 497

On the Methods of separating the undecomposed
Bodies from each other . . 499

General Observations; and Conclusion of Part First 502

ERRATA.

49, line 6, add lead.

71, line 3, /or silver tin, read silver and tin.
98, /or IV. read VI.

Ill, last Hne,/or phosphoranee reaflf phosphorana.

11-2, line 24,/or 15 to 1, read 1 to 15.

197, line 23 and 24,/or ordinary rea«f extraordinary, and

for extraordinary read ordinary.
292, first line of the note,/or 13.2 read 13. S.

319, line 7, /or 39 read 38.

320, line 19, erase palladium.
451, line 9,/or 18,5 read 24.

INTRODUCTION.

M GST of the substances belonging: to our
globe are constantly undergoing alterations in
sensible qualities, and one variety of matter
becomes as it were transmuted into another.

Such changes, whether natural or artificial,
whether slowly or rapidly performed, are called
chemical ; thus the gradual and almost imper-
ceptible decay of the leaves and branches of a
fallen tree exposed to the atmosphere, and the
rapid combustion of wood in our fires, are both
chemical operations.

The object of Chemical Philosophy is to as-
certain the causes of ail phaenomena of this
kind, and to discover the laws by which they
are governed.

The ends of this branch of knowledge are
the applications of natural substances to new
uses, for increasing the coDiforts and enjoy-
ments of man, and the demonslration of the

VOL. I. B

2

INTRODUCTION.

order, harmony, and intelligent design of the
system of the earth.

The foundations of chemical philosophy,
are observation, experiment, and analogy. By
observation, facts are distinctly and minutely
impressed on the mind. By analogy, similar
facts are connected. By experiment, new facts
are discovered; and, in the progression of know-
ledge, observation, guided by analogy, leads
to experiment, and analogy confirmed by expe-
riment, becomes scientific truth.

To give an instance. — Whoever will consider
with attention the slender green vegetable fila-
ments ( Conferva rivularis ) which in the sum-
mer exist in almost all streams, lakes, or pools,
under the different circumstances of shade and
sunshine, will discover globules of air upon
the filaments exposed under water to the sun,
but no air on the filaments that are shaded.
He will find that the effect is owing to the pre-
sence of light. This is an observation ; but it
gives no information respecting the nature of
the air. Let a wine glass filled with water be
inverted over the Conferva, the air will collect
in the upper part of the glass, and when the
glass is filled with air, it may be closed by the
hand, placed in its usual position, and an

INTRODUCTION. 3

inflamed taper introduced into it; the taper wiil
burn with more brilliancy than in the atmos-
phere. This is an experiment. If the pheno-
mena are reasoned upon, and the question is
put, whether all vegetables of this kind, in
fresh or in salt water, do not produce such air
under like circumstances, the enquirer is guided
hy analogy : and when this is determined to be
the case by new trials, a general scientific truth
is established — That all Confervae in the sun-
shine produce a species of air that supports
flame in a superior degree ; which has been
shewn to be the case by various minute inves-
tigations.

These principles of research, and combina-
tions of methods, have been little applied, ex-
cept in late times. A transient view of the
progress of chemical philosophy will prove
that the most brilliant discoveriesj and the
happiest theoretical arrangements belonging
to it are of very recent origin ; and a few histo-
rical details and general observations upon the
progress and effects of the science will form,
perhaps, no improper introduction to the ele-
ments of this branch of knowledge.

The only processes which can be called

chemical, known to the civilized nations of

B 2

4

introduction;

antiquity, belonged to certain arts, such as me-
tallurgy, dyeing, and the manufacture of glass
or porcelain ; but these processes appear to
have been independent of each other, pursued
in the workshop alone, and unconnected with
general knowledge.

In the early mythological systems of the
Egyptian priests, and the Braminsof Hindostan,
some views respecting the chemical changes of
the elements seem to have been developed,
which passed, under new modifications} iato
the theories of the Greeks ; but as the most
refined doctrines of this enlightened people,
concerning natural causes, in their best times,
were little more than a collection of vague spe-
culations, rather poetical than philosophical,
it cannot well be supposed that in earlier ages,
and amongst nations less advanced in cul-
tivation, there were any traces of genuine
science.

The inhabitants of Lower Egypt, where the
overflowing of the Nile covered a sandy desert
with vegetation and life, might easily adopt
the notion, that water, in different modifica-
tions, produced all the varieties of inanimate
and organized matter ; and this dogma charac"
tenzed the earliest school of Greece.

INTHODUeTION.

5

To generalize upon the great forms or powers
of nature, as elements, requires only very super-
ficial observation; and hence the theories seem
to have originated, which have been attributed
to Anaximander, and others of the early Greek
philosophers, concerning air, earth, water, and
fire.

As geometry and the mathematical sciences
became improved, mechanical solutions of the
changes of bodies were natural consequences,
such as the atomic philosophy of the Ionian
sect, and the five regular solids assumed by the
Pythagoreans as the materials ©f the universe.

In the beginning of the Macedonian dynasty,
the school of Aristotle gave a transient atten-
tion to the objects of natural science, but the
great founder attempted too many subjects to
be able to offer correct views of any one series.
— And his erroneous practice, that of advancing
general principles, and applying them to par-
ticular instances, so fatal to truth in all sciences,
more particularly opposed itself to the pro-
gress of one founded upon a minute examination
of obscure and hidden properties of natural
bodies.

Theophrastus, the successor of Aristotle, did
not, it appears, adopt the sublime, though purely

6

INTRODUCTION.

specujative doctrine of his master, the identity
of matter, and its diversity of form;* — for he
says, ill the beginning of his book concerning
fossils, ' stones are produced from earth, metals
from water. 'i — How such a notion as the last
could have been formed, it is difficult to dis-
cover ; yet, Theophrastus is perhaps the best
observer amongst the ancients, whose works
are in our possession, and the theories of this
distinguished teacher, who is said to have had
9. class of 2000 pupils, cannot be considered as
an unfavourable specimen of the theoretical
physics of the age.

In all pursuits which required only the na-
tive powers of the intellect, or the refinements
of taste, the Greeks were pre-eminent ; — their
literature, their works of art, offer models which
have never been excelled. They possessed, as
if instinctively, the perception of every thing
beautiful, grand, and decorous. As philoso-
phers, they failed not from a want of genius,
or even of application, but merely because they
pursued a false path, — because they reasoned

* 'E'TTH^h i'B tj (pt/o-K, ^»%aJs-, TO T8 sTJ'o; no.) ri vXrj. Aristotelis
Natural. Auscult. Lib. ii. 495, fol. Par. l654.

yh<i AtSof Tt %aX oa-a, hi^m cri^iTToTEjja, Theophrasti de Lapi-
dibus. Lug. Br. l6l3.

introduction;

more upon an imaginary system of nature, than
upon the visible and tangible universe.

It will be in vain to look in the annals of
Rome for science, that did not exist in Greece.
The conquerors became the pupils of the con-
quered ; and the Romans did little more than
clothe the systems of their masters in a new
dress, and adapt them to a new people.

The grand, but unequal poem of Lucretius,
contains the abstract of the opinions of Epi-
curus, compared with those of other celebrated
teachers. The Natural History of Pliny, is a
collection from all sources, but principally
from Theophrastus and Aristotle. The details
from his own observation are more interesting
when they relate to artificial, than when they
refer to natural operations ; the speculative no-
tions are of the rudest kind. The earlier phi-
losophical work of the Romans, as if indicative
of the youth of the people, is marked by power
and genius, by boldness and incorrectness ; the
later, as if it belonged to their old age, by gar-
rulity, copious and amusing anecdote, superr
stitious notions, and vulgar prejudices.

Some of the historians of this science,* in

* Many of the alchemical writers derive alchemy from
Tubal Cain ; others from Hermes Trismegistus, the Mercury

8

INTRODUCTION.

their zeal for the honour of its antiquity, hare
indeed endeavoured to find instances of an ac-
quaintance with some doctrines of practical
chemistry, atleast, amongst theancients. — Thus
Democritus is quoted by Laertius as having
employed himself in processes for imitating
gems, and for softening and working ivory.
Caligula is said to have made experiments with
the view of extracting gold from orpiment. —
Dioscorides, who is supposed to have been
physician to the celebrated Cleopatra, has
described the process of subliming mercury
from its ores. — Even Cleopatra herself, on
the evidence of such circumstances, might be
considered as an experimenter, because, in the
madness of profusion, she dissolved a pearl in
vinegar, and made a nauseous draught of a

of the Greeks. The first writing specifically on a chemical
subject, is a manuscript supposed to be of the fifth century,
by Zosimus, on the art of making gold and silver; which was
in the king's library at Paris. Suidas, who wrote in the ninth
or tenth century, mentions Diocletian as having burnt the
books of the Egyptians concerning the chemistry of silver
and gold : « TTEpt •xy^i'io.ti ufyvpa xot) x^van." Lexicon, Tom. i.
pag. 595.

For a minute investigation of the claims of the ancients to
chemical knowledge, the reader may consult Borrichius de
Ortu et Progress. Choem. Bergman. Opuscula, vol. IV. de pri-
iRordiis Chasm, and Lenglet Dufrenoy, Histoire de la Philoso-^
phie hermetique.

INTRODUCTION. 9

costly and^ beautiful substance; but it is idle
to relate such circumstances as indications of
science. If chemical operations had been known
to any extent, beyond their mere relations to the
arts, some mention of them might have been
expected in the medical writings of those
times ; but not even distillation is noticed in
the M^orks of Hippocrates or Galen; and the
same Dioscorides who has been just alluded to,
and who probably possessed vv^hatever know-
ledge was at that time extant in Egypt^ recom-
mends the use of a fleece of wool or a sponge,
for collecting the products from boiling or
burning substances.*

The origin of chemistry, as a science of
experiment, cannot be dated farther back than
the seventh or eighth century of the Christian
era, and it seems to have been coeval with the
short period in which cultivation and improve-
Kient were promoted by the Arabians.

The early Mahometans endeavoured to de-
stroy all the records of the former progress of
the human mind ; and, as if to make com-
pensation for this barbarian spirit, the same
people were destined, in a more adranced
period, to rekindle the light of letters, and to

* Dioscordis liber i. de picino oleo, pag 52.

10

INTRODUCTION.

become the inventors and cultivators of a new
science.

The early nomenclature of chemistry de-
monstrates how much it owes to the Arabians.
— The words alcohol, alkahest, aludel, alembic,
alkali, require no comment.

The first Arabian systematic works on
chemistry are said to have been composed
by Geber in the reigns of the caliphs Almainon
and Almanzor. The preparation of medicines
seems to have been the primary object in this
study ; and Rhases, Avicenna, and Avenzoar,
who have described various chemical opera-
tions in their works, were the celebrated phy-
sicians of the age.

Amongst a people of conquerors, disposed
to sensuality and luxury even from the spirit of
their religion, and romantic and magnificent
in their views of power, it was not to be ex-
pected that any new knowledge should be
followed in a rational and philosophical man-
ner ; and the early chemical discoveries led to
the pursuit of alchemy, the objects of which
were to produce a substance capable of con-
verting all ©tlier metals into gold ; and an uni-
versal remedy calculated indefinitely to prolong
the period of human life

INTRODUCTION.

11

Reasonings upon the nature of the metals,
and the composition of the philosopher's stone,
form a principal part of the treatises ascribed
to Geber ;* and the disciples of the School of
Bagdat seem to have been the first professed
alchemists.

It required strong motives to induce men to
pursue the tedious and disgusting processes of
the furnace ; but labourers could hardly be
wanting, when prospects so brilliant and mag-
nificent were oflfered to them ; the means of
procuring unbounded wealth ; of forming a
paradise on earth ; and of enjoying an immor-
tality depending on their own powers.

The processes supposed to relate to the
transmutation of metals, and the elixir of life,

* The library of the British Museum contains several
works bearing the name of Geber: amongst them are, De
Alchemia argentea, Speculum Alchemiae, et de Inventione
perfectionis : but they appear to be compilations formed
by alchemists of the loth and l6th centuries. Arsenic, mer-
cury, and sulphur, are considered in them as elements of
the metals ; distillation is distinctly described. Alcohol, cor-
rosive sublimate, and different saline combinations of iron,
tin, copper, and lead, are mentioned in them; but they
abound in obscure descriptions of mysterious processes, and
contain an account of some impracticable experiments. —
The Liber Fornacum is the most intelligible pari of the works
ascribed to Geber ; it contains a description of several metalur-
^ical operations, and of the common apparatus of the assaycr.

12

INTRODUCTION.

* were probably jErst made known to the Europe
cans during the time of the crusades— and
many of the warriors who, animated with
visionary plans of conquest, fought the battles
of their religion in the plains of Palestine,
seemed to have returned to their native coun-
tries under the influence of a new delusion.

The public spirit in the West, was calculated
to assist the progress of all pursuits that carried
with them an air of mysticism. Warm with the
ardor of an extending and exalted religion, men
were much more disposed to believe than to
reason ; — the love of knowledge and power is
instinctive in the human mind ; in darkness it
desires light, and follows it with enthusiasm even
when appearing merely in delusive glimmerings.

The records of the middle ages contain a
great variety of anecdotes relating to the trans-
mutation of metals, and the views or pretensions
of persons considered as adepts in alchemy:
these early periods constitute what may be re-
garded as the heroic or fabulous ages of che-
mistry. Some of the alchemists were low
impostors, whose object was to delude the cre-
dulous and the ignorant ; others seemed to
have deceived themselves with vain hopes ; but
all followed the pursuit as a secret and myste-

INTRODUCTION. 13

Tious study. T,h« processes were communicated
only to chosen disciples, and being veiled in the
most enigmatic and obscure language, their im-
portance was enhanced by the concealment. In
all times men are governed more by what they
desire or fear, than by what they know ; and in
this age it was peculiarly easy to deceive, but
difficult to enlighten, the public mind ; truths
were discovered, but they were blended with
the false and the marvellous; and another era
was required to separate them from absurdities,
and to demonstrate their importance and uses

Arnald of Villa Nova, who is said to have
died in 1250, was one of the earliest European
Enquirers who attended to chemical opera
tions. In the edition of the works ascribed to
him, published at Leyden in I509,* there are
several treatises on alchemical subjects, which
shew that he firmly believed in the transmu-
tation of metals ; the same opinions are attri-
buted to him and to Geber ; and he seems to
have followed the study with no ©thcr views
than those of preparing medicines, and attempt^
ing the composition of the philosopher's stone.

Raymund Lully of Majorca is said to have
been a disciple of Arnald, and applied himself

* Opera Arnaldi de Villa Nova, fol, 1509,

14

INTRODUCTION.

much more than his instructor to philosophy ;
but the works on general science, ascribed to
him, are more abundant in abstract metaphy-
sical propositions, than in facts; he followed,
in his physical views, the plan of Aristotle, and
our opinion of his chemical talents cannot be
very exalted, if the alchemical treatises bearing
his name be regarded as genuine documents.

Arnald and LuUy are both celebrated by the
vindicators of alchemy, as having been certainly
possessed of the secret of transmutation. Arnald
is said to have converted iron into gold at Rome ;
and it is pretended that Lully performed a si-
milar operation before Edward I. in London, of
which gold nobles were said to have been made.*

That the delusions of alchemy were ardently
pursued at this time may be learnt from a
reference to the public acts of these periods.
Pope John the S2d, who was raised to the pon-
tificate in the year 13 16, openly condemned
the alchemists as impostors, and the bull begins
by stating, that *' they promise what they do
not perform and in England an act of Par-
liament was passed in the fifth year of the reign
of Henry IV. prohibiting the attempts at
transmutation, and making them fclonious.f

* Bergman. Opuscula, Tom. IV. pag. 126.

t Lord Coke calls this act the shortest he ever met with.

INTRODUCTION.

15

Even in these times, however, there were
some few efforts to form scientific views. In
the beginning of the thirteenth century, Roger
Bacon of Oxford applied himself to experi-
ment, and his works offer proofs of talents,
industry, and sagacity. He tv^as a man of a truly
philosophical turn, desirous of investigating
nature, and of extending the resources of
art, and his enquiries offered some very
extraordinary combinations ; but neither his
labours, nor those of Albert of Cologne, his
contemporary, who appears to have been a
genius of a kindred character, had any con-
siderable influence on the improvement of
their age. The wonders performed by the ex-
perimental art were attributed by the vulgar
to magic ; and at a time when knowledge be-
longed only to the cloister, any new philosophy
was of course regarded even by the learned
with a jealous eye.

It would be a labour of little profit to dwell
upon the works of the professed alchemists
of the fourteenth and fifteenth centuries, of

5 H. IV. Statutes at large, Vol. I. page 457. " None from
henceforth shall use to multiply gold or silver, or use the craft
of multiplication, and if any the same do, he shall incur the
pain of felony."

16

INTRODUeilON.

Richard and Ripley in England, Isac in Hol-
land, Pico of Mirandula and Koffsky, in Poland.
The works attributed to these persons are of a
similar stamp,* and contain nothin*; which can
either instruct or amuse an intelligent reader.
Basil Valentine of Erfurt deserves to be sepa-
rated from the rest of the enquirers of this
age, on account of the novelty and variety of
his experiments on metallic preparations, par-
ticularly antimony: in his Currus triumphalis
Antimonii he has described a number of the
combinations of this metal. He used the
mineral acids for solutions, and seems to have
been one of the first persons who observed
the production of ether from alcohol. He
flourished about the year 14 i 3.

Cornelius Agrippa, who was born at Cologne
in 14865 openly professed magic, and endea-
voured to connect together judicial astrology,
the hermetic art, and metaphysical philosophy ;
and he was followed by Paracelsus, in Switzer-
land, and Digby, Kelly, and Dee, in England.

The first Arabian Alchemists seem to have
adopted the idea, that the elements were under

* Amongst them areRicardi AngU Libellus, wspt
Opus Saturni Johan. Isac, Compounde of Alchemy bj
George Ripley.

INTRODUCTION, 17

the dominion of spiritual beings, who might he
submitted to human power ; and the notions of
fairies and of genii, which have been depicted
with so much vividness of fancy and liveliness
of description in the Thousand and One
Nights, seem to have been connected with the
pursuit of the science of transmutation, and the
production of the elixir of life. The specu-
lative ideas of the Arabians were more or less
adopted by their European disciples. The Rosi-
crucian philosophy, in which gnomes, sylphs,
salamanders, and nymphs were the spiritual
agents, supposed capable of being governed or
enslaved by man, seems to have originated with
the Alchemists of this period ; and Agrippa,
Paracelsus, and their followers, above men-
tioned, all professed to believe in supernatural
powers, in an art above experiment, in a system
of knowledge not derived from the senses. It
would be a tedious and useless task, to describe
all the absurdities in the opinions and practices
of this school. Paracelsus alone deserves par-
ticular notice, from the circumstance of his
being the first public lecturer on chemistry
in Europe, and from the more important cir-
cumstance of his application of mercurial pre-
parations to the cure of diseases. The Magis-

VOL. I. C

is iNTROiilJdtlbN.

trates of Basle established a professor's chair for
their countryman, but he soon quitted an oc-
cupation in which regularity was necessary,
and spent his days in wandering from place to
place, searching for, and revealing secrets.
He pretended to confer immortality^ by his
inedicines, and yet died at the age of 49, at
Saltsburg, in the year I54I.*

The enthusiasm of this man almost supplied
his want of scenius. He formed a number of
new preparations of the metals, which were
Studied and applied by his disciples ; his exag-
gerated censure of the methods of the ancients,
and of the systems of his day, had an effect in
diminishing their popularity ; one error was
expelled by another ; and it is a great step to-
wards improvement, that men should knew
they have been in delusion.

Van Helmont, of Brussels, born in I58'§,t
was formed in the school of Alchemy, and his
mind was tinctured with its prejudices ; but
his views concerning nature and the elements
were distinguished by nmch more philosophi-
'cal aeutetiess, and more sagacity, than those of
any former writer. He is the first person who

^ Dictionnaire Historique, par Moreri, Tomeviii. pag»6^4.
1 1-bid Tom. v. pag, 570.

INTRODUCTION. 19

seems to have had any idea respecting elastic-
fluids, different from the air of the atmosphere
and he has distinctly mentioned three of these
substances, to which he applied the term gases ;
namely, aqueous gas or steam, unctuous or in-
flammable gas, and gas from wood or carbonic
acid gas. Van Helmont developed some accu-
rate views respecting the permanent elasticity
of air, and the operation of heat upon it ; and
a sketch of a curious instrument very similar to
the differential thermometer, is to be found in
his works.*

Van Helmont has used a term not so appli-
cable or intelligible as gas, namely, Bias ; which,
he supposed to be an influence derived from
the heavenly bodies, of a most subtile and
etherial nature ; and on the idea of its opera-
tions in our terrestial system, he has endea-
voured to found the vindication of astrology.-f-

At this period there was no taste in the pub-
lic mind to restrain vague imaginations. There
were no severe critics to correct the wander-
ings of genius. The systems of logic, adopted
in the schools were founded rather upon the

* Johan Baptist. Van Helmont, Opera Omnia, 4to. pag. 6l.
article Aer.
•j" Ibid. pag. 114.

C S

20

INTRODUCTION.

analogies of words, than upon the relations of
things ; and they were more calculated to con-
ceal error, than to discover truth. — Till the
revival of literature in Europe, there was no at-
tempt at philosophical discussion in any of the
sciences ; the diffusion of letters gradually
brought the opinions of men to the standard
of nature and truth ; failures in the experi-
mental arts produced caution, and the detection
of imposture created rational scepticism.

The delusions of Alchemy were exposed by
Guibert, Gassendi, and Kepler. Libavius an-
swered Guibert in a tone which demonstrated
the weakness of his cause. This person, who
died in 1616, was the last active experimentalist
who believed that transmutation had actually
been performed ; and in the beginning of the
1 7 th century the processes of rational chemistry
were pursued by a number of enlightened
persons in different parts of Europe.

A metallurgical School had before this time
been founded in Germany. George Agricola
published, in 1542, his twelve books, de Re
Metallica, or, on the methods of extracting
and purifying the useTul metals ,- and he was
followed by Lazarus Erckern. Assay Master
General of the Empire of Germany, whose

INTRODUCTION. 51

ivorts, brought forward in 15745 contain a
number of useful practices detailed in a simple
and perspicuous manner.

Lord Bacon happily described the Alche-
mists as similar to those husbandmen who in
searching for a treasure supposed to be hidden
in their land, by turning up and pulverising
the soil, rendered it fertile; in seeking for
brilliant impossibilities, they sometimes dis-
covered useful realities ; and in speaking of the
chemistry of his time, he says, a new philoso-
phy has arisen from the furnaces, which has
confounded all the reasonings of the ancients.
This illustrious man himself pointed out many
important objects of chemical enquiry ; but he
was a still greater benefactor to the science,
by his developement of the general system for
improving natural knowledge. Till his time
there had been no distinct views concernincr the
art of experiment and observation. Lord Bacon
demonstrated how little could be effected by
the unassisted human powers, and the weakness
of the strongest intellect even without artificial
resources. He directed the attention of inqui-
rers to instruments for assisting the senses,
and for examinins; bodies under new relations.
He taught that Man was but the servant and

t

INTRODUCTION.

interpreter of Nature ; capable of discovering
truth in no other way but by observing and
imitating her operations : that facts were to be
collected and not speculations formed : and
that the materials for the foundations of true
ystems of knowledge were to be discovered,
not in the books of the ancients, not in meta-
physical theories, not in the fancies of men,
but in the visible and tangible external world.

Though Van Helmonthad formed some just '
notions respecting the properties of air, yet his
views were blended with obscure and vas;ue
speculations, and it is to the disciples of Gal-
liljeoj that the true knowledge of the mecha-
nical qualities and agencies of elastic fluids is
owing. After Torricelli and Pascal had shewn
the pressure and weight of the atmosphere, the
investigation of its effects in chemical opera-
tions became an obvious problem.

John Rey is generally quoted as the first
person who shewed by experiments that air is
fixed in bodies during calcination : but it ap-
pears from the work of this acute and learned
man that he reasoned upon the processes of
others, rather than upon his own observations.

He quotes Fachsius, Libavius, Cesa]pin,and
Cardan, as having ascertained the increase of

INTRODUCTION. St$

weight of lead during its conversion into a
calx,* and he mentions an experiment of
Hammerus Poppius, who found that antimony
calcined by a burning-glass, notwithstanding th^
loss of vapours, yet was heavier after the process,

Rey ridicules the various notions of the Al«
chemists on the cause of this phsenomenon ; an4
ascribes it to the union of air with the metal ;
he supposes that air is miscible with other
bodies besides metals, and states distinctly that
it may be expelled from water.

The observations of John Rey seem to have
excited no attention amongst his cotemporaries.
The philosophical spirit was only beginning to
animate chemistry, and the labourers in this
science, occupied by their own peculiar pro-
cesses, were little disposed to listen to the rea-
sonings of an enquirer in general science ; yet,
though the most active of the forms of matter
were neglected in the processes of tlie operative
chemists of this day, and consequently no just
views formed by them, still they discovered a
number of important facts respecting the com-
binations and agencies of solid and fluid bodies.

* Sur la Recherche de la cause par kquelle Estain et le
Plomb au^pagntent de poids quaiid on les calcine. A Baiis
1630.

54 INTRODUCTION!.

Glauber at Amsterdam, about !640, mad»
known several neutral salts, and several conr-
pounds of metallic and vegetable substances,
Kunckel in Saxony and Sweden, pursued tech-
nical chemistry with very great success, and was
the first person who made any philosophical
experiments upon phosphorus, which was ac-
cidentally discovered by Brandt in 16^9.*
Barner in Poland, and Glaser in France, pub-
lished elementary books on the. science, and
Borichius in Denmark, Bohn at Leipzic, and
Hoffman at Halle pursued speciSc scientific in-
vestigations with much zeal and success ; and
Hoffm an was the first person who attempted the
philosophical analysis of mineral waters.

About the middle of this century likewise
mathematical and physical Investigations were
pursued in every part of the civilized world
with an enthusiasm before unknown. The new
mode of improving knowledge by collecting
facts, associated together a number of labourers
in the same pursuit. It was felt that the whole
of nature was yet to be investigated, that there
were distinct subjects connected with utility and
glory, sufficient to employ all enquirers, yet
tending to the common end of promoting the
* Horaberg, Mem. Acad. Paris, Tom. x. pag. 58.

INTRODUCTION

progress of the human mind. Learned bodies
were formed in Italy, England, and France, for
the purpose of the interchange of opinions, the
combination of labour and division of expense
in performing new experiments, and the ac-
cumulation and diffusion of knowledge.

The Academy del Cimento was established
in 1651 under the patronage of the Duke of
Tuscany ; the Royal Society of London, in
1660 ; the Royal Academy of Sciences of Paris,
in 1666. And a number of celebrated men, who
have been the sireat luminaries of the different
departments of science, were brought together
or formed in these noble establishments. The
ardour of scientific investigation was excited
and kept alive by sympathy: taste was improved
by discussion, and by a comparison of opinions.
The conviction that useful discoveries would
be appreciated and rewarded, was a constant
stimulus to industry, and every field of enquiry
was open for the free and unbiassed exercise of
the powers of genius.

Boyle, Hooke, and Slare, were the principal
early chemical investigators attached to the
Royal Society of London. Homberg, Geoffroy,
and the two Lemerys, a few years later, dis"
tinguished themselves in France*

S6 INTRODUCTION.

Otto de Guericke of Magdeburgh invented
the air pump ; and this instrument, improved
by Boyle and Hooke, was made an important
apparatus for investigating the properties of
air. Boyle* and HQoke,+ from their experi-
ments, concluded that air was absolutely ne-
cessary to combustion and respiration, and that
one part of it only was employed in these pro-
cesses. And Hooke formed the sagacious con-
clusion, that this principle is the same as the
substance fixed in nitre, and that combustioi; is
a chemical process, the solution of the burning
body in elastic fluid, or its union with this
matter.

Mayow of Oxford, in 1674, published his
treatises on the nitro-atrial spirit, in which he
advanced opinions similar to those of Boyle
and Hooke, and supported them by a number
of original and curious experiments ;:|: but his
work, though marked by strong ingenuity,
abounds in vague hypotheses. He attempted
to apply the imperfect chemistry of his day to

* Boyle's Works, Vo. iv. page 90.

f Hooke's Micrographia, page 45, 104, 105.

X Tract, p. 28. He has particularly assigned the cause of
the calcination of metals, " Quippe vix concipi potest unde
augmentum illud antimonii nisi a particulis nitro Mreis i§-
»eisque inter calcinajajlum fixis procedat."

IJTTRODUGTION. 27

physiology ; his failure was complete, but it
was the failure of a man of genius.

Boyle was one of the most active experi**
menters, and certainly the greatest chemist of
his age. He introduced the use of tests or
reagents, active substances for detecting the
presence of other bodies : he overturned the
ideas which at that time were prevalent, that
the results of operations by fire were the real
elements of things, and he ascertained a num-
ber of important facts respecting inflammable
bodies, acids, alkalies, and the phcenomena of
combination ; but neither he nor any of his
contemporaries endeavoured to account for
the changes of bodies by any fixed principles'.'
The solutions of the phasnomena were at-
tempted either on rude mechanical notions, or
by occult qualities, or peculiar subtile spiritjS
or ethers supposed to exist in the different bo-
dies.— And it is to the same great genius who
developed the laws that regulate the motions of
the heavenly bodies, that chemistry owes the
first distinct philosophical elucidations of the
powers which produce the changes and appa^
rent transmutations of the substances belon<r-
ing to the earth.

Sugar dissolves in water, alkalies unite with
acids, metals dissolve in acids. Is mi 'ikk^ says

I

2$ INTRODUCTION.

Newton, on account of an attraction between
their particles ? Copper dissolved in aquafortis
is thrown down by iron. Is not this because
the particles of the iron have a stronger at-
traction for the particles of the acid, than
those of copper ; and do not different bodies
attract each other with dijBTerent degrees of
force ? *

A few years after Newton had brought for-
wards these sagacious views, the elder Geoffroy
endeavoured to ascertain the relative attractive
powers of bodies for each other, and to arrange
them in an order in which these forces, which
he named, affinities, were expresed.+

Chemistry had scarcely begun to assume the
form of a science, when the attention of the
most powerful minds were directed to other
objects of research the same great man who
bestowed on it its first accurate principles, in
some measure impeded its immediate progress,
by his more important discoveries in optics,
mechanics, and astronomy

These objects of the Newtonian philosophy
were calculated by their grandeur, their simpli-
city, and their importance, to become the study
of the men of most distinguished talents ; the

* Newton's Works, quarto, Tom. iv. page 242.
t Mfemoires del' Academic, 17I8, page 256.

INTRODUCTION. S9

effect that they occasioned on the scientific
mind may be compared to that which the new
sensations of vision produce on the blind re-
ceiving sight; — they. awakened the highest in-
terest, the most enthusiastic admiration, and for
nearly half a century, absorbed the attention
of the most eminent philosophers of Britain
and France.

Germany still continued the great school of
practical chemistry, and at this period it gained
an ascendancy of no mean character over the
rest of Europe in the philosophy of the science.
Beccher, who was born at Spires in I645, after
having studied with minute attention, the ope-
rations of metallurgy, and the phaenomena of
the mineral kingdom, formed the bold idea of
explaining the whole system of the earth by
the mutual agency and changes of a few ele-
ments. And by supposing the existence of a
vitrifiable, a metallic, and an inflammable earth,
he attempted to account for the various produc-
tions of rocks, crystalline bodies, and metallic
veins, assuming a continued interchange of
principles between the atmosphere, the ocean,
and the solid surface of the globe, and consi-
dering the operations of nature as all capable
©f being imitated by art.

so NTRODUCTION.

The Phfsica suhterranea, and the Oedipus
chemicus of this author, are very extraordinary
productions." They display the efforts of a vi-
gorous mind, the conceptions of a most fertile
imagination, but the conclusions are too rapid-
ly formed ; there is a want of logical precision
in his reasonings ; the objects he attempted
v^ere grand, but his means of execution compa-
ratively feeble. He endeavoured to raise a per-
fect and lasting edifice upon foundations too
Weak, from materials too scanty and not suf-
ficiently solid ; and the work, though magni-
ficent in design, was rude unfinished and
feeble, and rapidly fell into decay.

Beccher added very little to the collection
of chemical experiments, but he improved the
instruments of research, simplified the mani-
pulations, and by the novelty and boldness of
'his speculations, excited enquiry amongst his
disciples.

His most distinguished follower was George
Ernest Stahl, born in 1660, who soon attained
a reputation superior to that of his master, and
developed doctrines which for nearly a century
constituted, the theory of chemistry of the
whole of Europe.

Albertus Magnus had advanced the idea thact

INTRODUCTION. 3^

the mfetals were earthy substances impregnated
with a certain inflammable principle. Becchet
supported the idea of this principle, not only
as the cause of metallization, but likewise of
combustibility : and Stahl endeavoured, by a
number of ingenious and elaborate experiments,
to prove the existence of phlogiston, as it
was called, and to explain its agencies in the
phaenomena of nature and art.

'Glauber, about fifty years before Stahl begafi
liis labours, had discovered the combination of
fossil alkali and sulphuric acid, which still
bears his name. And Stahl, in operating upon
this body, thought he had discovered the proof,
tliat the inflammability not only of metals, but
likewise of all other substances, was owing to
the same principle. Charcoal is entirely dis-
sipated or consumed in combustion, therefore,
says this philosopher, it must be phlogiston
nearly 'pure ; by heating charcoal with metallic
earths, they become metals ; therefore they
are compounds of metallic earths and phlogis-
ton : by heating Glauber's salt, which consists of
sulphuric acid and fossil alkali, with charcoal,
a compound of sulphur and alkali is obtained ;
therefore sulphur is an acid combined with
phlogiston. Stahl entirely neglected the che-

3S INTRODUCTION.

mical influence of air on these phenomena ; and
though Boyle had proved that phosphorus
and sulphur would not burn without air, and
had stated that sulphur was contained in sul-
phuric acid, and not the acid in sulphur, yet
the ideas of the Prussian school were received
without controversy. Similar opinions were
adopted in France by Homberg and Geoffroy,
who assumed them without reference to the
views of the Prussian philosopher, and opposed
them to the more correct and sagacious views
of the English school of chemistry.

Though misled in his general notions, few
men have done more than Stahl for the pro-
gress of chemical science.— His processes were,
many of them, of the most beautiful and satis-
factory kind : he discovered a number of
properties of the caustic alkalies and metallic
calces, and the nature of sulphureous acid ;
he reasoned upon all the operations of che-
mistry in which gaseous bodies were not con-
cerned, with admirable precision. He gave
an axiomatic form to the science, banishing
from it vague details, circumlocutions and
enigmatic descriptions, in which even Beccher
had too much indulged ; he laboured in the
spirit of the Baconian school, multiplying in*

INTRODUCTION. 33

Stances, and cautiously making inductions, and
appealing in all cases to experiments which,
though not of the most refined kind, wer«
more perfect than any which preceded them.

Dr. Hales, about 17 24, resumed the investi-
gations commenced with so much success by
Boyle, Hooke, and Mayow; and endeavoured to
ascertain the chemical relations of air to other
substances, and to ascertain by statical expe-
riments the cases in nature, in which it is
absorbed or emitted. He obtained a number of
important and curious results ; but, misled by
the notion of one elementary principle con-
stituting elastic matter, and modified in its
properties by the effluvia of solid or fluid
bodies, he formed few inferences connected
with the refined philosophy of the subject:
he disengaged, however, elastic fluids from
a number of substances, and drew the con-
clusion that air was a chemical element in many
compound bodies, and that flame resulted from
the action and re-action of serial and sulphurous
particles.*

In 1756 Dr. Black publisiied his admirable
researches on calcareous, magnesian, and al-
kaline substances, by which he proved the

• Hales' Statical Essays, 2d ed. 8vo. Vol. i, pag. 315.
VOL. I. D

34 INTRODUCTION.

existence of a gaseous body, perfectly distinct
from the air of the atmosphere. He shewed that
quicklime differed from marble and chalk by
containing this substance, and that it was a
weak acid, capable of being expelled from
alkaline and earthy substances by strong
acids.*

Ideas so new and important as those of the
British philosopher, were not received without
opposition ; several German enquirers endea-
voured to controvert them. . Meyer attempted
to shew that limestones became caustic, not
by the emission of elastic matter, but by com-
bining with a peculiar substance in the fire ;
but the loss of weight was perfectly inconsistent
with this view: and Bergman atUpsal, Macbride
in Ireland, Keir at Birmingham, and Cavendish
in London, demonstrated the correctness of the
opinions of Black; and a few years were suffi-
cient to establish his theory upon immutable
foundations.

The knowledge of one elastic fluid different
from air, immediately led to the enquiry
whether there might not be others. The pro-
cesses of fermentation which had been observed

* Essays and Observations Physical and Literary, vol. ii.
page 1 59,

INTRODUCTION. 35

by the ancient chemists, and those by which
Hales had disengaged and collected elastic
substances, were now regarded under a novel
point of view ; and the consequence was, that
a number of new bodies, possessed of very ex-
traordinary properties, were discovered.

Mr. Cavendish, about 1765, invented an ap-
paratus for examining elastic fluids confined
by water, which has been since called the
hydro-pneumatic apparatus. He discovered
inflammable lair, and described its properties ;
he ascertained the relative weights of fixed air,
inflammable air, and common air, and made a
number of beautiful and accurate experiments
on the properties of these elastic substances.

Dr. Priestley, in I771j entered the same in-
teresting path of enquiry ; and principally by
repeating the processes of Hales, added a
number of most important facts to this depart-
ment of chemical philosophy. He discovered
nitrous air, nitrous oxide, and dephlogisticated
air; and by substituting mercury for water in the
pneumatic apparatus, ascertained the existence
of several aeriform substances, which are rapidly
absorbable by water, muriatic acid air, sul-
phurous acid air, and ammonia.

Whilst a new branch of the science was

$6

INTRODUCTION.

making this rapid progress in Britain, the che»
mistry of solid and fluid substances was pursued
with considerable zeal and success in France
and Germany ; and Macquer, Rouelle, Mar-
graff, and Pott, added considerably to the
knowledge of fosslle bodies, and the proper-
ties of the metals. Bergman, in Sweden, de-
veloped refined ideas on the powers of chemi-
cal attraction, and reasoned in a happy spirit
of generalization on many of the new phaeno-
mena of the science ; and in the same country
Scheele, independently of Priestley, discovered
several of the same aeriform substances : he
ascertained the composition of the atmosphere;
he brought to light fluoric acid, prussic acid,
and the substance which has been improperly
called oxymuriatic gas.

Black, Cavendish, Priestley, and Scheele,
were undoubtedly the greatest chemical dis-
coverers of the eighteenth century ; and their
merits are distinct, peculiar, and of the most
exalted kind. Black made a smaller number
of original experiments than either of the
other philosophers ; but being the first labourer
in this new department of the science, he
had greater dilEcukies to overcome. His me*
ihods are distinguished for their simplicity,

INTRODUCTION.

37

his reasonings are admirable for their pre-
cision; and his modest, clear, and unaffected
manner, is well calculated to ~ impress upon
the mind a conviction of the accuracy of his
processes, and the truth and candour of his
narrations.

Cavendish was possessed of a minute know-
ledge of most of the departments of Natu-
ral Philosophy ; he carried into his chemical

researches a delicacy and precision, which
have never been exceeded: possessing depth

and extent of mathematical knowledge, he
reasoned with the caution of a geometer upon
the results of his experiments : and it may be
said of him, what, perhaps, can scarcely be
said of any other person, that whatever he
accomplished, was perfect at the moment of
its production. His processes were all of a
finished nature ; executed by the hand of a
master, they required no correction ; the accu-
racy and beauty of his earliest labours even,
have remained unimpaired amidst the progress
of discovery, and their merits have been illus-
trated by discussion, and exalted by time.

Dr. Priestley began his career of discovery
without any general knowledge of chemistry,
and with a very imperfect apparatus. His

3^

INTRODUCTION.

characteristics were ardent zeal and the most
unwearied industry. He exposed all the sub-
stances he could procure to chemical agencies,
and brought forward his results as they oc-
curred, without attempting logical method or
scientific arrangement. His hypotheses were
usually founded upon a few loose analogies ;
but he changed them with facility ; and being
framed without much effort, they were relin-
quished with little regret. He possessed in the
highest degree ingenuousness and the love of
truth. His manipulations, though never very
refined, were always simple, and often inge-
nious. Chemistry owes to him some of her most
important instruments of research, and many
of her most useful combinations; and no single
person ever discovered so many new and cu-
rious substances.

Scheele possessed in the highest degree the
faculty of invention ; all his labours were in-
stituted with an object in view, and after happy
or bold analogies. He owed little to fortune
or to accidental circumstances : born in an ob-
scure situation, occupied in the duties of an
irksome employment, nothing could damp the
ardour of his mind or chill the fire of his ge-
nius : with rery small means he accomplished

INTRODUCTION. S9

very great things. No difficulties deterred
him from submitting his ideas to the test of
experiment. Occasionally misled in his views,
in consequence of the imperfection of his ap-
paratus, or the infant state of the inquiry, he
never hesitated to give up his opinions the
moment they were contradicted by facts. He
was eminently endowed with that candour
which is characteristic of great minds, and
which induces them to rejoice as well in the
detection of their own errors, as in the dis-
covery of truth- His papers are admirable
models of the manner in which experimental
research ought to be pursued ; and they con-
tain details on some of the most important and
brilliant phasnomena of chemical philosophy.

The discovery of the gasses, of a new class
of bodies, more active than any others in most
of the phaenomena of nature and art, could
not fail to modify the whole theory of che-
mistry. The ancient doctrines were revised;
new modifications of them were formed by
some philosophers ; whilst others discarded
entirely all the former hypotheses, and endea-
voured to establish new generalizations.

The idea of a peculiar principle of mflam-
mability was so firmly established in the

40 INTRODUCTION.

chemical schools, that even the knowledge of
the composition of the atmosphere for a long
while was not supposed to interfere with it ; and
the part of the atmosphere which is absorbed by-
bodies in burning, was conceived to owe its
powers to its attraction for phlogiston.

All the modern chemists who made experi-
ments upon combustion, found that bodies in-
creased in weight by burning, and that there
was no loss of ponderable matter. It was ne-
cessary therefore to suppose, contrary to the
ideas of Stahl, that phlogiston was not emitted
in combustion, but that it remained in the in-
flammable body after absorbing gaseous mat-
ter from the air. But what is phlogiston was
a question constantly agitated. Inflammable air
had been obtained during; the dissolution of cer-
tain metals, and during the distillation of a num-
ber of combustible bodies. This light and sub-
tile matter, therefore, was fixed upon as the prin-
ciple of inflammability ; and Cavendish, Kirwan,
Priestley, and Fontana, were the illustrious
advocates of this very ingenious hypothesis.

In 1774, Bayen* shewed that mercury con-
veirted into a calx or earth, by the absorption of
air, could be revived without the addition of
* Journal de Physique, 1774, page 28S,

INTRODUCTION. 4I

any inflammable substance ; and hence he con-
cluded, that there was no necessity for sup-
posing the existence of any peculiar principle
of inflammability, in accounting for the calcin-
ation of metals. The subject, nearly about the
same time, was taken up by Lavoisier, who had
been for some time engaged in repeating the ex-
periments of the British philosophers. Bayen
formed no opinion respecting the nature of the
air produced from the calx of mercury. Lavoi-
sier, in 1775, shewed that it was an air which
supported flame and respiration better than com-
mon air, which he afterwards named oxygene ;
the same substance that Priestley and Scheele
had procured from other metallic substances the
year before, and had particularly described.*

Lavoisier discovered that the same air is pro-
duced during the revivification of metallic
calces by charcoal, as that which is emitted
during the calcination of limestone; hence he
concluded, that this clastic fluid is composed
of oxygene and charcoal; and from his expe-
riments on nitrous acid and oil of vitriol, he

* In the Journal de Physique for l/^P, Preliminary Dis-
course, De la Meiherie has given an adrnir<ible \ieworihe
progress of the investigations concerning the gases. See
p. 24, &c.

42 INTRODUCTION.

concluded that this gas entered into the compo-
sition of these substances.

Dr. Black had demonstrated by a series of
beautiful experiments, that when gases are con-
densed, or when fluids are converted into solids,
heat is produced. In combustion gaseous mat-
ter usually assumes the solid or the fluid form.
Oxygene gas, said Lavoisier, seems to be
compound of the matter of heat, and a basis.
In the act of burning, this basis is united to the
combustible body, and the heat is evolved.
There is no necessity, said this acute philoso-
pher, to suppose any phlogiston, any pecu-
liar principle of inflammability ; for all the
phaenomena may be accounted for without this
imaginary existence.

Lavoisier must be regarded as one of the
most sagacious of the chemical philosophers
of the last century ; indeed, except Cavendish,
there is no other inquirer who can be compared
to him for precision of logic, extent of view,
and sagacity of induction. His discoveries
were few, but he reasoned with extraordinary
correctness upon the labours of others. He
introduced weight and measure, and strict
accuracy of manipulation into all chemical
processes. His mind was unbiassed by pre-

INTRODUCTION* 43

judice ; his combinations were of the most phi-
losophical nature : and in his investigations
upon ponderable substances, he has entered
the true path of experiment with cautious steps,
following just analogies, and measuring hypo-
theses by their simple relations to facts.

The doctrine of Lavoisier, soon after it was
framed, received some important confirmations
from the two grand discoveries of Mr. Caven-
dish, respecting the composition of water, and
nitric acid ; and the elaborate and beautiful in-
vestigations of Berthollet respecting the nature
of ammonia; in which phacnomena, before ano-
malous, were shewn to depend upon combina-
tions of aeriform matter.

The notion of phlogiston, was however de-
fended for nearly 20 years, by some philoso-
phers in Germany, Sweden, Britain, and Ire-
land. Mr. Cavendish, in 17 84, drew a parallel
between the hypothesis, that all inflammable bo-
dies contain inflammable air, and the doctrine in
which they are considered as simple substances,
in a paper equally remarkable for the precision
of the views displayed in it, and for the accu-
racy and minuteness of the experiments it con-
tains. To this great man, the assumption of
M. Lavoisier, of the matter of heat, appeared

44

INTRODUCTION,

more hypothetical than that of a principle of
inflammability. He states, that the phaenomena
may be explained on either doctrine ; but he
prefers the earlier view, as accounting, in a
happier manner, for some of the operations of
nature.

De Morveau, Berlhollet, and Fourcroy, in
France, and William Higgins and Dr.Hope,in
Britain, were the first advocates for the anti-
phlogistic chemistry. Sooner or later, that doc-
trine which is an expression of facts,must prevail
over that which is an expression of opinion. The
most important part of the theory of Lavoisier
was merely an arrangement of the facts relating
to the combinations of oxygene: the principle
of reasoning which the French school professed
to adopt was, that every body which was not
yet decompounded, should be considered as
simple ; and though mistakes were made with
respect to the results of experiments on the
nature of bodies, yet this logical and truly phi-
losophical principle was not violated ; and
the systematic manner in which it was en-
forced, was of the greatest use in promoting
the progress of the science.

Till 17 86, there had been no attempt to
reform the nomenclature of chemistry ; the

INTRODUCTION.

45

names applied by discoverers to the substances
which they made known, were still employed.
Some of these names, which originated amongst
the alchymists, were of the most barbarous
kind ; few of them were sufficiently definite
or precise, and most of them were founded
upon loose analogies, or upon false theoretical
views.

It was felt by many philosophers, particu-
larly by the illustrious Bergman, that an im-
provement in chemical nomenclature was ne-
cessary, and in 1787, Messrs. Lavoisier, Mor-
veau, Berthollet, and Fourcroy, presented to
the world a plan for an almost entire change
in the denomination of chemical substances,
founded upon the idea of calling simple bodies
by some names characteristic of their most
striking qualities, and of naming compound
bodies from the elements which composed
them.

The new nomenclature was speedily adopted
in France ; under some modifications it was
received in Germany ; and after much discus-
sion and opposition, it became the language of
a new and rising generation of chemists in
England. It materially assisted the diffusion of
the antiphlogistic doctrine, and even facilitated

46

INTRODUCTION.

the general acquisition of the science ; and
many of its details were contrived with much
address, and were worthy oF its celebrated au-
thors: but a very slight reference to the phi-
losophical principles of language will evince
that its foundations were imperfect, and that
the plan adopted was not calculated for a pro-
gressive branch of knowledge.

Simplicity and precision ought to be the
characteristics of a scientific nomenclature :
words should signify things, or the analogies
of things, and not opinions. If all the elements
were certainly known, the principle adopted by
Lavoisier would have possessed an admirable
application ; but a substance in one age sup-
posed to be simple, in another is proved to
be compound ; and vice versa. A theoretical
nomenclature is liable to continued alterations;
oxygenated muriatic acid is as improper a
name as dephlogisticated marine acid. Every
school believes itself in the right ; and if every
school assumes to itself the liberty of altering
the names of chemical substances, in conse-
quence of new ideas of their composition, or
decomposition, there can be no permanency in
the language of the science, it must always
be confused and uncertain. Bodies which are

INTRODUCTION. 47

similar to each other should always be classed
together ; and there is a presumption that their
composition is analogous. Metals, earths, al-
kalies, are appropriate names for the bodies
they represent, and independant of all specu-
lative views ; whereas oxides, suiphurets, and
muriates, are terms founded upon opinions of
the composition of bodies, some of which have
been already found erroneous. The least dan-
gerous mode of giving a systematic form to a
language, seems to be, to signify the analogies
of substances by some common sign affixed to
the beginning or the termination of the word.
Thus, as the metals have been distinguished by
a termination in um, as aurum, so their calci-
form or oxidated state, might have been denot-
ed by a termination in a, as aura ; and no pro-
gress, however great, in the science, could ren-
der it necessary that such a mode of appellation
should be changed. Moreover, the principle
of a composite nomenclature must always be
very limited. It is scarcely possible to repre-
sent bodies consisting of five or six elements
in this way, and yet it is in such difficult cases
that a name implying a chemical truth would
be most useful.

The new doctrines of chemistry, before 1795,

4t

INTRODUCTION.

were embraced by almost all the active expe-
rimental enquirers in Europe ; and the adoption
of a precise mode of reasoning, and more re-
fined forms of experiment, led not only to the
discovery of new substances, but likewise to a
more accurate acquaintance with the properties

and composition of bodies that had long been
known.

New investigations were instituted with re-
spect to all the productions of nature, and the
immense variety of substances in the mineral,
vegetable, and animal kingdom, submitted to
chemical experiments.

The analysis of mineral bodies first at-
tempted by Pott in experiments principally on
their igneous fusion, and afterwards refined by
the application of acid and alkaline menstrua,
by Margraaf, Bergman, Bayen, and Achard,
received still greater improvements from the
labours of Klaproth, Vauquelin, and Hatchett.
Hoffman, in the beginning of the 1 8th century,
pointed out magnesia as a peculiar substance.*
Margraaf, about fifty years later,f distinguished
accurately betweea the silicious, calcareous, and

* Hoffman, Opera, Tom. iv. pag. 47.9.
t Opuscules, Tom. ii. pag. 137.

INTRODUCTION. 49

aluminous earths, Scheele, in 1774, discovered
barytes. Klaproth,* in 1 788, made known zir-
cone. Dr. Hope,f strontites in 791» Qadolin,
ittriajin 1794; and Vauquelin, glucine in I798.

Seven metals only had been accurately known
to the ancieats, gold, silver, mercury, copper,
tin, and iron. Zinc, bismuth, arsenic, and anti-
mony, though mentioned by the Greek and
Roman authors, yet were employed only in
certain combinations, and the production of
them in the form of reguli or pure metals, was
owing to the Alchemists.

Cobalt had been used to tinge glass ia
Saxony in the sixteenth century ; but the me-
tal was unknown till the time of Brandt, and
this celebrated Swedish chemist discovered it
in 17 33' Nickel j| was procured by Cronstedt
in 1751. The properties of manganese, which
was announced as a peculiar metal by Kaim ^
in 1 7 70, were minutely investigated by Scheele
and Bergman a few years after. Molybdic acid
was discovered by Scheele in 177 8, and a metal
procured from it by Hielm in 1782, the same

* Annales de Chiraie, Tom. i. pag. 183.
+ Edinburgh Trans. Vol. iv. p. 44.
X Crell's Annals, 1796.
H Bergman Opuscula, Tpin. ii. page 22c
I De Metallis dubiis, p. 48.
VOL. I. ^

so

INTRODUCTION.

year that tellurium was made known by Muller.
Scheele discovered tungstic acid in 17 Si; and
soon after a metal was extracted from it by
Messrs. D' Elhuyars. Klaproth discovered
uranium in 1 7 89,* The first description of the
properties of the oxide of titanium was given
by Gregor in 1791-+ Vauquelin made known
chromium in 1797 ;$ Hatchett columbium in
1801;§ and skortly after, the same substance
was noticed by Ekeberg, and named by him
tantalium. Cerium was discovered in I804, by
Hissinger and Berzelius. Platina had been
brought into Europe and examined by Lewis in
1749* and in I803, Descotils, Fourcroy, and
Vauquelin announced a new metallic substance
in it ; but the complete investigation of the pro-
perties of this extraordinary body was reserved
for Messrs. Tennant and WoUaston, who in
1 803 and 1804 discovered in it no less than four
new metallic substances, besides the body which
exists in it in the largest proportion, namely,
iridium, osmium, palladium, and rhodium.

The attempts made to analyse vegetable
lubstances previous to 17^0, merely produced

* Jntirnal de Physique, 17S9. pag. 39.
t Aniiales de ('himie, xii. pag. 147. I Ibid, xxv. 21.
Phil. Trans. i8u2.

I

INTRODUCTION. 51

their resolution into the supposed elements of
the chemists of those days, namely, salts, Earths,
phlegm, and sulphur. Boerhaave and Newmann
attempted an examination by fluid menstrua,
which was pursued with some success by Rou-
elle, Macquer and Lewis. Scheele, between 17 70
and 17.80, pointed out several new vegetable
acids. Fourcroy, Vauquelin, Deyeux, Seguin,
Proust, Jacquin, and Hermbstadt, between 17 80
and 1790, in various interesting series of expe-
riments, distinguished between different secon-
dary elements of vegetable matter, particu-
larly extract, tannin, gums, and resinous sub-
stances ; and investigations of this kind have
been pursued with great success by Hatchett,
Pearson, Shraeder, Chenevix,Gehlen,Thomson,
Thenard, Chevreul, Kind, Brande, Bostock^
and Duncan. The chemistry of animal sub-
stances has received great elucidations from
several of the same enquirers ; and Berzelius
has examined most of their results, and has
added several new ones, in a comprehensive
work expressly devoted to the subject, pub-
lished in 1S08.

That solid masses fell from above, connected
with the appearance of meteors, had been
advanced as early as 500 years before the

Eg

52 INTRODUCTION.

Christian aera, by Anaxagoras ; and the same idea
had been brought forward in a vague manner
by other enquirers amongst the Greeks and
Romans, and was revived in modern times ;
but till 1802 it was regarded by the greater
number of philosophers as a mere vulgar error,
when Mr. Howard, by an accurate examina-
tion of the testimonies connected with events
of this kind, and by a minute analysis of the
substances said to have fallen in different parts
of the globe, proved the authenticity of the
circumstance, and shewed that these meteoric
productions differed from any substances be-
longing to our earth ; and since that period a
number of these phscnomena have occurred,
and have been minutely recorded.

The philosophy of heat, the foundations of
which were laid between 1757 and 11 $5, by
Black, Wilcke, Crawford, Irvine, and Lavoisier,
since that period has received some new and
very important additions, from the inquiries of
Pictet, Rumford, Herschel, Leslie, Dalton,
and Gay Lussac. The circurosfances under
which bodies absorb and communicate heat,
have been minutely investigated ; and the
important discoveries of the different physical
and chemical powers of the difterent solar

INTRODUCTION. 5S

rays; and of a property analogous to polarity
in light, bear immediate relation to the most
refined doctrines of corpuscular science, and
promise to connect^ by close analogies, the
chemical and mechanical laws of matter.

A general view of the philosophy of che-
mistry was published under the name of Chemi-
cal Statics, in 1 803, by the celebrated Berthollet.
It is a work remarkable for the new views that
it contains on the doctrines of attraction ; views
which are still objects of discussion, and which
bear an immediate relation to some of the con-
clusions depending upon very recent disco-
veries.

At the time when the antiphlogistic theory
was established, electricity had little or no re-
lation to chemistry. The grand results of
Franklin, respecting the cause of lightning,
had led many philosophers to conjecture, that
certain chemical changes in the atmosphere,
might be connected with electrical phseno-
mena; — and electrical discharges had been
employed by Cavendish, Priestley, and Van-
marum, for decomposing and igniting bodies ;
but it was not till the era of the wonderful
discovery of Volta, in i860, of a new electrical
apparatus, that any great progress was made in

54

INTRODUCTION.

chemical investigation by means of electrical
coHibinations.

Nothing tends so much to the advancement
of knowledge as the application of a new in-
strument. The native intellectual powers of
men in different times, are not so much the
causes of the different success of their labours,
as the peculiar nature of the means and artificial
resources in their possession. Independent of
vessels of glass, there could have been no accu-
rate manipulations in common chemistry : the
air pump, was necessary for the investigation of
the properties of gaseous matter ; and without
the Voltaic apparatus, there was no possibility
of examining the relations of electrical pola-
rities to chemical attractions.

By researches, the commencement of which is
owing to Messrs. Nicholson and Carlisle, in 1800,
which were continued by Cruickshank, Henry,
Wollaston, Children, Pepys, Pfaff, Desormes,
Biot, Thenard, Hissinger, and Berzelius, it
appeared that various compound bodies were
capable of decomposition by electricity; and ex-
periments, which it was my good fortune to in-
stitute, proved that several substances which had
never been separated into any other forms of
matter in the common processes of experiment,

INTRODUCTION. 53

were susceptible of analysis by electrical
power'4 ; in consequence of these circumstances,
the fixed alkalies and several of the earths have
been shewn to be metals combined with oxy-
gene ; various new agents have been furnished to
chemistry, and many novel results obtained by
their application, which at the same time that
they have strengthened some of the doctrines of
the school of Lavoisier, have overturned others,
and have proved that the generalizations of the
Antiphlogistic philosophers were far from hav-
ing anticipated the whole progress of discovery.

Certain bodies which attract each other che-
mically, and combine when their particles have
freedom of motion, when brought into con-
tact, still preserving their aggregation, exhibit
what may be called electrical polarities ; and by
certain combinations these polarities may be
highly exalted ; and in this case they become
subservient to chemical decompositions ; and
by means of electrical arrangements the con-
stituent parts of bodies are separated in an uni-
form order, and in definite proportions.

Bodies combine with a force, which in many
cases is correspondent to their power of exhibit-
ing electrical polarity by contact ; and heat, or
heat and light, are produced in proportion to the

56

iNTftODUGTlON.

energy of their combination. Vivid inflam-
mation occurs in a number of cases in which
gaseous matier is not fixed; and this phseno-
menon happens in various instances without
the interierence of. free or combined oxygene.

Experiments made by Richter and Morveau
had shewn that, when there is an interchange
of elements between two neutral salts, there is
never an excess of acid or basis ; and tlie same
law seems to apply generally lo double de-
compositions. When one body combines with
another in more than one proportion, the se-
cond proportion appears to be some multiple or
divisor of the first ; and this circumstance, ob-
served and ingeniously illustrated by Mr. Dal-
ton, led him to adopt the atomic hypothesis of
chemical changes, which had been ably defended
by Mr. Higgins in 1789, namely, that the che-
mical elements consist of certain indestructible
particles which unite one and one, or one and
two, or in some definite numbers.

Whether matter consists of indivisible cor-
puscles, or physical points endowed with
attraction and repulsion, still the same conclu-
sions may be formed concerning the powers
by which they act, and the quantities in which
they combine ; and the powers seem capable of

INTRODUCTION. 57

being measured by their electrical relations, and
the quantities on which they act of being ex-
pressed by numbers.

In combination certain bodies form regular
solids; and all the varieties of crystalline ag-
gregrates have been resolved by the genius of
Haiiy into a few primary forms. The laws of
crystallization, of definite proportions, and of
the electrical polarities of bodies, seem to be
intimately related; and the complete illustra-
tion of their connection, probably will constitute
the mature age of chemistry.

To dwell more minutely upon the particular
merits of the chemical philosophers of the pre-
sent age, will be a grateful labour for some future
historian of chemistry ; but for a contemporary
writer, it would be indelicate to assume the
right of arbitrator, even where praise only can
be bestowed. The just fame of those who have
enlightened the science by new and accurate
experiments, cannot fail to be universally ac-
knowledged; and concerning the publication
of novel facts there can be but one judgment ;
for facts are independent of fashion, taste, and
caprice, and are subject to no code of cri-
ticism ; they are more useful perhaps even
when they contradict, than when they support

58

INTRODUCTION.

received doctrines, for our theories are only im-
perfect approximations to the real knowledge
of things ; and in physical research, doubt is
usually of excellent elFect, for it is a principal
motive for new labours, and tends continually
to the developement of truth.

The slight sketch that has been given of the
progress of chemistry, has necessarily been
limited to the philosophical details of discovery.
To point out in historical order the manner
in which the truths of the science have been
applied to the arts of life, or the benefits
derived by society from them, would occupy
many volumes. From the first discovery of
the production of metals from rude ores, to the
knowledge of the bleaching liquor, chemistry
has been continually subservient to cultivation
and improvement. In the manufacture of porce-
lain and glass, in the arts of dying and tanning,
it has added to the elegancies, refinement, and
comforts of life ; in its application to medicine
it has removed the most formidable of diseases ;
and in leading to the discovery of gunpowder,
it has changed the institutions of society, and
rendered war more independent of brutal
strength, less personal, and less barbarous.

It is indeed a double source of interest in

INTRODUCTION.

59

this science, that whilst it is connected with
the grand operations of nature, it is likewise
subservient to the common processes as well as
the most refined arts of life. New laws cannot
be discovered in it, without increasing our ad-
miration of the beauty and order of the sys-
tem of the universe; and no new substances
can be made known which are not sooner or
later subservient to some purpose of utility.

When the great progress made in chemistry
within the last few years is considered, and the
number of able labourers who are at present
actively employed in cultivating the science,
it is impossible not to augur well concerning
its rapid advancement and future applications.
The most important truths belonging to it are
capable of extremely simple numerical ex-
pressions, which may be acquired with facility
by students ; and the apparatus for pursuing
original researches is daily improved, the use
of it i^endered more easy, and the acquisition
less expensive.

Complexity almost always belongs to the
early epochs of every science; and the grandest
results are usually obtained by the most simple
means, A great part of the phaenomena of
chemistry may be already submitted to calcu-

60

INTRODUCTION.

lation ; and there is great reason to believe,
that at no very distant period the whole science
will be capable of elucidation by mathematical
principles. The relations of the common me-
tals to the bases of the alkalies and earths, and
the gradations of resemblance between the
bases of the earths and acids, point out as pro-
bable a similarity in the constitution of all in-
flammable bodies : and there are not wantin<r
experiments, which render their possible de-
composition far from a chimerical idea. It is
contrary to the usual order of things, that
events so harmonious as those of the system of
the earth, should depend on such diversiied
agents, as are supposed to exist in our artificial
arrangements; and there is reason to antici-
pate a great reduction in the number of the
undecompounded bodies, and to expect that
the analogies of nature will be found con-
formable to the refined operations of art. The
more the phaenomena of the universe are stu-
died, the more distinct their connection appears,
the more simple their causes, the more magni-
ficent their design, and the more wonderful the
wisdom and power of their Author.

ELEMENTS

OF

CHEMICAL PHILOSOPHY.

PART I.

ON THE LAWS OF CHEMICAL CHANGES

ON

UNDECOMPOUNDED BODIES

AND

THEIR PRIMARY COMBINATIONS.

ELEMENTS, 8fc.

DIVISION I.

ON THE POWERS AND PROPERTIES OF MAT-
TER, AND THE GENERAL LAWS OF CHEMICAL
CHANGES.

I. Preliminary Observations.

1. 1. H E forms and appearances of the beings
and substances of the external world are almost
infinitely various, and they are in a state of
continued alteration : the whole surface of the
earth even undergoes modifications : acted on
by 'moisture and air, it affords the food of
plants ; an immense number of vegetable pro-
ductions arise from apparently the same mate-
rials ; these become the substance of animals ;
one species of animal matter is converted into
another ; the most perfect and beautiful of the
forms of organised life ultimately decay, and
are resolved into inorganic aggregates; and
the same elementary substances, differently

[ 64 ]

arranged, are contained in the inert soil, or
bloom and emit fragrance in the flower, or be-
come in animals the active organs of mind and
intelligence. In artificial operations changes of
the same order occur; substances having the cha-
racters of earths are converted into metals ; clays
and sands are united so as to become porcelain ;
earths and alkalies are combined into glass ;
acrid and corrosive matters are formed from
tasteless substances ; — colours are fixed upon
stuffs, or changed, or made to disappear; and
the productions of the mineral, vegetable, and
animal kingdoms are converted into new forms,
and made subservient to the purposes of civil-
ized life.

2. To trace in detail these diversified and
complicated phsenomena, to arrange them and
deduce general laws from their analogies, would
be a labour to which even the longest life of the
most industrious and sagacious individual might
be devoted in vain. The student who has the
advantage of referring to the knowledge accu-
mulated by many individuals in different times,
may adopt much more simple methods of acquir-
ing the science. Those of recurring to its general
principles, so as to ascertain the powers and
properties of matter, which are the causes of
the phaenomena of Chemistry; and of apply-
ing these principles to the actions taking place

[ 65 ]

be<^ween tbe various substances existing in
nature, or produced by art ; proceeding gradu-
ally referring to ob<;ervations, experiments, and
distinct analogies, from the more simple to the
more complicated changes, so as to understand
the laws by which they are governed.

11. Of the Forms of Matter,

1. In the general views that may be taken of
the properties of natural substances, certain
relations appear, which afford the means of
arranging them in four distinct classes, each of
which is distinguished by certain sensible and
obvious qualities,

2. The first class consists of solids ^ which
compose the great known part of the globe.
Solid bodies, when in small masses, retain what-
ever mechanical form is given to them : their
parts are separated with difficulty, and cannot
readily be made to unite after separation ; some
solid bodies yield to pressure, and do not reco-
ver their former figure, when the compressing
force is removed, and they are called non-elas-
tic solids ; others that regain this form, are called
elastic bodies. Solids differ in degrees of hard-
ness, in colour, in degrees of opacity or trans-
parency, in density or in the weight afforded by
equal volumes ; and when their forms are regu-
lar or crystallized, in the nature of these forms.

VOL. I. F

[66]

3. The second class consists o£ fluids, of whicK
there are much fewer varieties. Fluids when in
small mrsses assume the spherical form ; theix
parts possess freedom of motion ; they differ in
degrees of density and tenacity, in colour and
degrees of opacity or transparency. They are
usually regarded as incompressible, at least a
very great mechanical force is required to make
them occupy a space perceptibly smaller.

4- Elastic fluids or gasses the third class
exist free in the atmosphere ; but they may be
confined by solids, or by solids and fluids, and
their properties examined. Their parts are
highly move;able ; they are compressible and
expansible, and their volumes are inversely as
the weights compressing them. All known
elastic fluids are transparent, and present only
two or three varieties of colour ; they differ
materially in density.

5. Besides these forms of matter which are
easily submitted to experiment, and the parts
of which may be considered as in a state of ap-
parent rest, there are other forms of matter
which are known to us only in their states of
motion when acting upon our organs of sense,
or upon other matter, and which are not suscep-
tible of being confined. They have been some-
times called etherial substances^ which appears a,
more unexceptionable name than imponderable

[67l

substances. It cannot be doubted that there is
matter in motion in space, between the sun and
th^ stars and our globe, though it is a subject
of discussion whether successions of particles be
emitted from these heavenly bodies, or motions
communicated by them, to particles in their vi-
cinity, and transmitted by successive, impulses
to other particles. Etherial matter differs either
in its nature or in its affections by motion ; for
it produces different effects; for instance, as
radiant heat, and as different kinds of light.

6. The various forms of matter, and the
changes of these forms, depend upon active
powers, such as gravitation, cohesion, calorific
repulsion or heat, chemical attraction, and elec-
trical attraction, the laws of which it is neces-
sary to study with attention.

III. Kjrravitation.

1. When a stone is thrown into the atmo-
sphere it rapidly descends towards the surface
of the earth. This is owing io gravitation. All
the great bodies in the universe are urged to»
wards each other by a similar force. A cannon
ball sent from a piece of artillery describes a
curve, and at last falls to the ground ; were the
impulse given to it by the gunpowder, increased
to a certain extent, and exerted in free space, it
would continuously revolve round the earth, in

[ 68 1

consequence of the equilibrium between the two
forces. The moon and the planets as Newton
has demonstrated, are retained in their orbits
by simiiar laws, and their harmonious and con-
stant revolutions produced.

2. Bodies mutually gravitate towards each
other; but the smaller body proportionally
more than the larger one : hence the power of
gravity is said to be directly as the mass; it is
in fact the measure of the mass or quantity of
matter.

3- Gravitation acts inversely, as the square of
the distance.

IV. Cohesion.

1. When two particles of quicksilver are
brought into apparent contact they may be
made to unite and form one globule : when a
glass tube, having a very JSne bore, is intro-
duced into a vessel containing water, the water
rises in the tube to a higher level than it occu-
pied in the vessel : both these effects are said to
be owing to cohesion or cohesive attraction. It is
the same force which preserves the forms of
solids, and gives globularity to fluids, and is
thus a prime cause of the permanency of the
arrangements which compose the surface of the
globe. It is usually said to act only at the sur-
faces of bodies, or by their immediate contact ;
but this does not seem to be the case. It

[ 69 ]

certainly acts with much greater energy at small
distances ; but the spherical form of minute
portions of fluid matter can only be produced
by the attractions of all the parts of which they
are composed, for each other ; and most of these
attractions must be exerted at sensible distances,
so that for any thing we know to the contrary,
gravitation and cohesion may be mere modifi-
cations of the same general power of attraction,
in the one case acting at distances that can be
easily measured, and in the other case operat-
ing at distances which it is difficult to estimate.

2. Some philosophers have attempted to ac-
count for attraction in general by supposing that
there is a certain unknown matter always mov-
ing through the universe in right lines, by which
bodies are impelled towards each other ; but
though the phasnomena may be explained by
such a supposition, it is without proof; and
there is no ground for supposing that matter
cannot act at a distance, and it is absolutely
necessary for the explanation of the planetary
motions, to suppose space in the universe yoid
of matter.

V. Of Heat, or calorific Repulsion.

1. When a body which occasions the sen-
sation of heat on our oro;ans, is brou2:ht into
contact with another body which has no suck

[ 70 ]

effect, the result of their mutual action is that
the hot body contracts, and loses to a certain
extent its power of communicating heat, and
the other body expands, and in a degree ac-
quires this power.

This law may be exemplified with respect to
every form of ponderable matter. If a polished
cylinder of tin, which accurately fits a ring, be
heated so as to make water boil, it will no lonser
pass through the ring, and will be found en-
larged in all its dimensions. If spirits of wine
be heated in a glass vessel having a narrow
tubulated neck, as it becomes capable of com-
municating the sensation of heat, it will be
found to expand and to rise in the narrow
neck ; and if the body of the same vessel be
filled with air, and it be inverted in water, its
neck containing water, the air will rapidly ex-
pand, on the application of a heated body, and
will cause the water to descend in the neck of
the vessel.*

2. Different solids and fluids expand very
differently when heated by the same means.

Glass is less expansible than any of the
metals ; 100,000 parts raised from the degree
of freezing to that of boiling water, expand so
as to become 100,083 parts ; 100,000 of plati-
nurai under similar circumstances expand so as
* Plate I. fig. 1.

t 71 ]

to become 100,087 ; and equal parts oF gold,
antimony, cast-iron, steel, iron, bismutli, cop-
per, cast-brass, silver, tin, lead-zinc, and ham-
inered zinc expand in the following order :
100094, 100108, 1001 tl, 100112, 100126,
100139, 100170, 100189, 100238, 100287,
100296, 100308. The expansive power of
liquids in general is greater than that of solids ;
alcohol appears to be more expansible than
oils, and oils in general more expansible than
water. 100,000 parts of mercury of the same
degree of heat as ice become at the degree of
heat at which water boils 101,835. All the
elastic fluids, or the different species of air that
have been examined, as has been demonstrated
by Messrs. Dalton and Gay Lussac, expand
alike when heated to the same degree; 100
parts of each at the freezing point of water be-
coming about 137j5 at the boiling point.

It is evident that the density of bodies must
be diminished by expansion ; and in the case
of fluids and gasses, the parts of which are
mobile, many important phenomena depend
upon this circumstance. If heat be applied to
fluids or to gasses, the heated parts change
their places and rise ; and the colder parts
descend and occupy their places. Currents are
constantly produced in the ocean and in great
bodies of water, in consequence of this ellect.

[72]

The heated water rises to the surface in the
tropical climates, and flows towards coldt r ones,
thus the warmth of the Gulf stream is felt a
thousand miles from its source ; and de^p cur-
rents pass from the colder to the warmer parts
of the sea: and the general tendency of these
changes is to equalize the tetuperature of the
globe.

In the atmosphere, heated air is constantly-
rising, and colder air rushes in to supply its
place ; and this event is the principal cause of
winds : the air that flows from the poles towards
tlie equator, in consequence of the rotation of
the earth, has less motion than the atmos-
phere into which it passes, and occasions an
easterly current ; the air passing from the
equator towards the poles having more motion,
occasions a westerly current ; and by these
changes, the different parts of the atmosphere
are mixed together : cold is subdued by heat,
moist air from the sea is mixed with dry air
from the land, and the great mass of elastic
fluid surrounding the globe, preserved in a state
fitted for the purposes of vegetable and animal
life.

S. There are very few exceptions to the law of
the expansion of bodies, at the time they become
capable of communicating the sensation of heat ;
and these excepiions seem entirely to depend

[ 73 ]

upon some chemical change in the constitution
of bodies, or on their crystalline arrangements.
Thus clay contracts considerably in dimensions
by a very intense heat, and on the measure of
its contractions the pyrometer of Wedgwood
is founded : but in this case the clay first gives
ofF water, which was united to its parts, and
afterwards these parts cohere together with
more force, and from being in a state of loose
aggregation become strongly united. Water
expands a little before it congeals, and expands
considerably during its conversion into ice ; but
in this case it assumes the crystalline form ;
and its parts whilst they are arranging them-
selves to form regular solids, probably leave
greater interstices than they occupied when at
uniform distances in the fluid. Thus the same
weight of matter will occupy much more space
when arranged in a certain number of octahe-
drons, than when arranged in a similar number
of cubes, or hexagonal prisms. Certain saline
solutions likewise that shoot into prismatic
crystals, expand at the moment they become
solid ; and the case is the same with cast-iron,
bismuth, and antimony.

The expansion of water during its conversion
into ice, is shewn by the circumstance of ice
swimming upon water ; and if water in a deep
vessel be examined at the time ice is forming, it

[ u 3

ivill he found a little warmer at the bottom than
at the top ; and these circumstances are of
great importance in the ioeconomy of nature.
Water congeals only at the surface, where it is
liable to be acted upon hy the sun, and by
warm currents of air which tend to restore ittd
the fluid state; and when water approaches
near the point of freezing it begins to descend^
so that no ice can form till the whole of the
water has been cooled to the point where it
possesses the greatest density ; and in the deep
parts of the sea and lakes, even in some of the
northern latitudes, the duration of the long
winter is insufficient to cool the water to the
degree at which ice forms.

4. When equal quantities of the same matter
differently heated are mixed together, as much
as the one contracts, so much the other seems
to expand. It is easy to prove this by shaking
together 100 parts of mercury so hot as not to
be touched without pain, and 100 parts in its
common state, having previously measured the
space they occupy ; if the mixture is made in
the tube that contained the hot mercury, there
will be no sensible change of volume.

It is on the idea, that when heat or the
power of repulsion is communicated from body
to body, as much is gained by one body as
is lost by the other, that thermometers have

been framed, and the doctrines of temperature^
and Capacity for heat founded,

5. The most common thermometer is a glass
bulb, containing mercury, terminated by a glass
tube, having a very narrow bore. The mer-
cury is boiled to expel any air or moisture that
might be attached to it ; and at the moment
it is in ebullition, the extremity of the tube
being drawn to a fine point, is hermetically
sealed by a spirit lamp. For the purpose o£
acquiring a scale, the bulb is first plunged into
melting ice, and the place where the mercury
stands is marked ; the bulb is afterwards
plunged into boiling water and the same ope-
ration repeated. On Fahrenheit's scale this
space is divided into 180 equal parts, and simi-
lar parts are taken above and below for extend-
ing the scale, and the freezing point of water
is placed at S2**, and the boiling point at 212°.
1.8 degrees of Fahrenheit are equal to one de-
gree of the centigrade thermometer, and 2.25 to
one degree of Reaumur.

Other fluids besides mercury, such as alcohol,
are sometimes used in thermometers, particu-
larly for measuring low degrees when mercury
freezes.

Air is employed in the differential thermo-
meter, which consists of two bulbs filled with
air, and connected by a capillary tube contain-

[ 76 ]

ing oil of vitriol ; the heated body is brought
in contact with one bulb, the air of which
expands and drives the fluid towards the other
bulb.*

6. Temperature is the power bodies possess of
communicating or receiving heat, or the energy
of repulsion ; and the temperature of a body is
said to be high or low with respect to another,
in proportion as it occasions an expansion or
contraction of its parts ; and the therraometer
is the common measure of temperature.

7. When equal volumes of different bodies of
different temperatures are suffered to remain in
contact till they are possessed of the same tem-
perature, it is found that this temperature is
not a mean one, as it would be in the case of
equal volumes of the same body. Thus, if a
pint of quicksilver at 100°, be mixed with a
pint of water at 50°, the resulting temperature
is not 75°, but about 70° : the mercury has lost
30**, whereas the water has gained only 20°.
In the common language of chemical philoso*
phers this difference is said to depend upon
the different capacities of bodies for heat, and
the capacity of a body is said to be greater or

• Plate 1. fig. 2, represents Mr. Leslie's differential thermo-
meter. Fig. 3 is copied from Van Helmont. This instrument
appears to have been the first in which the expansive power of
heated air, was exhibited by its action upon cold air.

[ 11 1

less, in proportion as its temperature is less or
more raised by the addition, or diminished by
the subtraction of equal quantities of the
power of repulsion, or heat. Thus mercury
is said to have a much less capacity for heat
than water ; and taking the facts above stated as
data, and comparing the weights of the two
bodies, which are as I3.3 to 1, their capacities
will be to each other as about I9 to 1.

Tables of the relative capacities of bodies are
given in the works of different authors. In re-
ferring to the various bodies which are the
subjects of chemistry, this property will be de-
scribed amongst other properties. ' In general
it appears that the substances most expansible
by heat are those which have the greatest capa-
cities ; thus gasses in general have greater
capacities than fluids, and fluids than solids;
but the exact ratio has not been yet deter-
mined.

8. Different bodies, it appears, have their
temperatures differently raised by the addition,
or diminished by the subtraction of equal
quantities of heat, or the power of repulsion,
and they are likewise affected by heat, or ex-
panded with very different degrees of celerity.
If slender cyhnders of silver, of glass, and of
charcoal, of equal length and size, be held in
the central part of the flame of a candle, tLe

[ 78 }

silver rapidly becomes heated throughout, and
cannot be held in the hand; the heat is more
slowly communicated through the glass, but
the charcoal becomes red-hot at the one extre-
mity long before any heat is felt at the other
extremity. These differences are said to de-
pend upon the different pov*^ers of these bodies
for conducting heat; thus the silver is said to
be a better conductor than the glass, and the
glass than the charcoal. In general those bodies
that are the densest, and that have the least
capacity for heat, are the best conductors ; thus
the metals conduct better than any other solids ;
gasses are worse conductors than fluids, and
fluids than solids: but there are exceptions
with respect to this correspondence between
conducting power and density, and a remarka-
ble one, in the densest known body in nature,
platlna, which is perhaps the worst conductor
amongst the metals.

Animal and vegetable substances in general,
are very bad conductors ; thus the hair and
wool of animals, and the feathers of birds, are
admirably fitted to protect them from the cold,
and they inclose and retain air, which being a
still worse conductor, enhances the effect. It
was supposed by Count Rumford, that fluids
and gasses are perfect nonconductors of heat, and
that their particles can be heated in no other

[ 79 ]

way, except by coming in succession to the
source of heat ; but some very conchisive ex-
periments seem to render this opinion untena-
ble. In general, however, fluids and gasses
alter their places, from a change of specific
gravity much more rapidly than they communi-
cate or receive heat. This is iUostrated by a
very simple experiment; let an air thermometer
be inverted in a vessel of wAter, so that the ex-
tremity of the bulb is barely beneath the surface,
let a little ether be poured upon the water so
as to form a stratum about -f- of an inch above
the thermometer, and let the ether be in-
flamed ;* however delicate the thermometer, the
^ir in it will not soon expand ; the ether boils
violently, but a very long process of this kind
is required to communicate any sensible heat
to the water. Unless the particles of gasses and
fluids had been capable of communicating heat
to a certain extent, the upper strata of liquids
would be almost the only permanently heated
parts ; and heat would be constantly accumu-
lating on the surface of extensive seas. Our
lower atmosphere likewise would be intensely
cold during the absence of the sun ; but by the
relations between the conducting power and the
mobility of fluids and gasses ; the changes offem-
perature of air and water are made progressive
« See Plate I. fig. 4.

[ 80 ]

and equable, and adapted to a habitable globe.
As heat is propagated very slowly through
gaseous bodies, so they communicate it very
slowly to other bodies, a circumstance that
might be expected from the small quantity of
matter they contain, when compared to other
substances. The heat of metals at the tempera-
ture of 120° is scarcely supportable; water
scalds at 150°; but air may be heated to 240°
without being painful to our organs of sen-
sation, and a temperature near this was expe-
rienced for some minutes, by Sir Joseph Banks,
Sir Charles Blagden, and Dr. Fordyce, in a
room artificially heated.

The power of abstracting heat in air is like-
wise comparatively very small ; in the high
northern latitudes a cold has been experienced
without injury, in which mercury froze ; and if
in this state of the atmosphere, metallic sub-
stances, of the same temperature, were touched,
a sensation like that of burning was experienced,
and the part blistered.

9. Heat, or the power of repulsion, may be
considered as the antagonist power to the attrac-
tion of cohesion, the one tending to separate,
the other to unite the parts of bodies ; and the
forms of bodies depend upon their respective
agencies. In solids the attractive force pre-
dominates over the repulsive ; in fluids, and in

[ «1 1

elastic fluids they may be regarded as in dif-
ferent states of equilibrium ; and in ethereal
substances the repulsive must be considered as
predominating over, and destroying the attrac-
tive force.

All the different substances in nature, under
certain circumstances, are probably capable of
assuming all these forms ; thus solids, by a cer-
tain increase of temperature, become fluids, and
fluids gasses; and rice versa, by a diminution
of temperature gasses become fluids, and fluids
solids;

Instances of the fusion of solids by heat are too
familiar to require any particular notice ; when
water becomes steam by boiling, it is merely
the conversion of a fluid into an elastic fluid ;
and a simple instance of this circumstance may
be given in the ebullition of ether. Let a little
ether be introduced into a small glass retort
filled with water, and inverted in water ; the
ether will swim above the water, in the upper
part of the retort; let a heated bar of metal* be
held near the part of the retort containing the
ether, as the heat is communicated, globules
will be seen to rise, and in a very short time
elastic fluid will be formed, in such quantities,
as to expel the water from the vessel; on suf-

Plate I. fig. 5.

VOL. I. G

[ 82 1

ferirsg the glass to cool, the elastic matter will
be condensed, and will become again Huid.

If a globule of mercury be held in a spoon
oF platina, over the flame of a lamp, it wiil be
vividly agitated, and will rapidly diniinish.
This is owing to its becoming elastic, and flying
off in gas; and by a very low temperature,
which may be artificially produced by mixing
together very cold snow and a salt called muri-
ate of lime, mercury may be congealed into the
solid form.

JDifFerent bodies change their states at very
diETerent temperatures. Thus mercury, which
is a solid at about 40 below Fahrenheit, boils
at about 66O ; sulphur, which becomes fluid at
218% boils at 570°; ether boils at 9'S°. The
temperatures at which the common metals be-
come gaseous, are generally very high, and
most of them incapable of being produced by
common means. Iron, manganese, platina,
and some other metals, which can scarcely be
fused in the best furnaces, are readily melted
by electricity; and by the Voltaic apparatus a
degree of heat is attained, in which platina not
only fuses with readiness, but seems even to
evaporate:

With respect to the conversion of solids,
fiiiids, or gasses, into ethereal substances, the;

[ 83 ]

proofs are hot of the same distinct nature as
those belonging to their conversion into each
other. When the temperature of a body is
raised to a certain extent, it becomes lumin-
ous ; and heated bodies not only affect other
bodies by direct contact, but likewise exert an
influence on them at a distance, which is as-
cribed to what is usually called radiant heat.
One solution of this phenomenon is, that par-
ticles are thrown off from heated bodies with
great velocity, which by acting on our organs
produce the sensations of heat or light, and
that their motion, communicated to the particles
of other bodies, has the power of expanding
them ; thus if heat, or the force of repulsion,
be so increased in an elastic fluid, as to over-
come the force of cohesion and gravitation, these
particles would move in right lines through
free space ; and we know of no other effects
they could produce, than those of heat and
light. It is perhaps in favour of this opinion,
that all the different elastic fluids expand
equally, when their temperatures are equally
raised; and from observations made on the
eclipses of Jupiter's satellites, and from other
phenomena presented by the heavenly bodies,
it appears that the motions of light are equable.
It may, however, be said, that the radiant

mafters emitted by bodies in ignition, are spe-
cific substances, and that common matter is not
susceptible of assuming; this form; or ii may-
be contended, that the phenomena of racli.iiion
do, in fact, depend upon motions communicated
to subtile matter every where existing in space.

9. The temperatures at which boflies change
their states from fluids to solids, though in
general definite, are influenced by a few cir-
cumstances, such as mrtion and psessure.
Water, kept perfectly at rest, may sometimes be
cooled to 22° without cone;e!aii!>n : hut if at a
temperatute below 52°, it be agitated, ice in-
stantly forms, A saturated solution of Gl .uber's
salt, introduced whilst warm into a boltle. frc m
which the pressure of tlse atmosphere is ex-
cluded, remains liquid after cooling, but if the
atmc sphere be suffered to act upon it, it in-
stantly crystallizes. The boiling point of
fluids is still less fixed, than-the point of fusion
of solids, and is immediately dependent upon
pressure. Thus ether will boil readily at the
freezing point of water, in the exhausted re-
ceiver of an air pump ; and it appears from the
researches of Professor Robison, that in a
vacuum, all liquids boil about bwer, than,
in the open air. Under pressure, liquids may-
be heated to.a high degree ; water in a Papin's

C 85 3

digester, may have its temperature raised to
S'OO', but at the moment the pressure is removed,
elastic matter is disengap^ed with great violence.

10. A peculiar distinction has been made
by some autliors between permanent eiaslic
Ouids, and elastic fluids which are conderisi-
ble by pressure or cold ; but these substances
differ only in the degree of the point of va:;or-»
ization ; and steam at 5Qu decrees of Faiiren-
heit, there is every reason to beh'eve, would
be equaliy incondensibie with air at a range
of temperature such as we can commimd btlow
our common temperatures; and some gassts
that are permanent under all common circum-
stances, as ammonia, are condensible by intense
cold aided by pressure.

Ali bodies that boil at moderate temperatures,
seem to evaporate, so as to produce a certain
quantity of elastic matter in the common state
of the atmosphere ; and this quantity is greater
in proportion as the temperature is high. Ac-
cording to Mr. Dalton, the force of vapour in-
creases in geometrical progression to the tem-
perature, but thiE ratio differs in different fluids.
It is certain that as the temperature approaches
near the point of ebullition, in liquids, the
strength of the vapour, i. e. the quantity that
would rise in free space, rapidly increases.

In h©t, dry weather, it is obvious that tliere

[ 86 3

must be much more vapour in the atmosphere,
than in cold wet weather; and the largest
quantity exists in summer and in the tropical
climates, when moisture is most needed for the
purposes of life ; and it appears to be the
aqueous vapour in the atmosphere, which,
when condensed by the mixture of cold with
hot air, or by other agencies occasioning a
change of its temperature, is the cause of dew,
mists, rain, and ultimately of springs, and
rivers.

11. When solids are converted into fluids, or
fluids into gasses, there is always a loss of heat,
of temperature, and vice versa, when gasses
are converted into fluids, or fluids into solids,
there is an increase of heat of temperature,
and in this case it is said that latent heat is ab-
sorbed or given out. Thus if equal weights of
snow at and of water at 172° be mixed to-
gether, the whole of the snow is melted, but
the temperature of the mixture is found to be
32°} so that 140" degrees of heat are lost. Again,
if water be heated in a Papin's digester to 300
degrees, and the valve be raised, a quantity of
steam instantly rises, which has the temperature
of 212°, and the temperature of the water in
the digester is found to be the same, so that a
great quantity of heat of temperature is lost in
eonvertino; the water into steam.

[S7J

% when the'air is at 20", a quantity of water
Wexposed to it in a tall glass, the water gra-
dually cooh down to 22°, without freezina;, but
if it be shaken, So as to be converted into ice,
the temperatuie of the ice is found to be at 32°
so that the degree of heat is raised during the act
offreezlns.

If one part of steam or aqueous gas, at 212°,
be mixed with 6 parts by \veig;ht of water at
62°, the whole of the steam will be condensed,
and the temperature of the fluid will be about
512°, so that there is an immense increase of
the heat of temperature, and 900° degrees may
be considered as taken from the steam, and as
added to the water.

All the phenomena of these changes may be
referred to a simple general law, of which Dr,
Black was the discoverer, and which has been
most ably illustrated by the researches of
Wilke, Watt, Irvine, and Crawford, namely,
" that whenever a body changes its form, its
relations to temperature are likewise changed,
either increased or diminished;" and many im-
portant operations, both artificial and naturalj
depend upon this law. The knowledge of it,
for instance, led Mr. Watt to make his great
improvement ot* the steam engine, by which the
steam is condensed out of the cylinder in which

[ 8g

its forceis efficient, and fresh gaseous matter intro-
duced vvithoutany chance of a loss of its elasticity.

One of the most perfect modes of heating
large rooms, and of procuring a uniform tempe-
rature for the purposes of manufacture, is by
the condensation of steam. By the cold pro-
duced in consequence of the evaporation of
water in hot climates, congelation is effected ;
and in the nights in Bengal, when the tempe-
rature is not below fifty, by the exposure of
water in earthenware pans upon moistened
bamboos, thin calces of ice are formed, which
are heaped together and preserved under ground
by being kept in contact with bad conductors
of heat. The cold produced by evaporation,
is likewise the cause of the formation of ice in
Mr. Leslie's elegant experiment, in which sul-
phuric acid is placed in a vessel upon the plate
of an air-pump, and water in another vessel
raised above it ; the surfaces both of the acid
and the water being considerable. When an
exhaustion is made, the sulphuric acid rapidly
absorbs the vapour rising from the water;
fresh vapour is immediately formed, and in a
few minutes, if the circumstances are favour-
able, spicule of ice are seen to form on the
surface of the water.

When aqueous vapour is condensed into

[ 89 ]

fluid in tTie atmosphere, heat is produced ; and
the for mat ion of rain, hail, and snow, tends to
miti^^ate the severity of the winter. In the sum-
mer, evaporation is constantly tending to cool the
surface. The melting of the polar ice moder-
ates the heat that would arise in the northern
regions from the constant presence of the sun
during the polar summer. And the evolution of
heat during the congelation of water, prevents
too great a degree of cold, and renders the
transitions of temperature more slow and
gradual.

- 12. When the forms of bodies are changed
by mechanical means, or when mechanical
forces are made to act upon them, there is
usually a change of temperature. A piece of
caotchouc extended and suffered to contract
rapidly by mechanical means, becomes hot ; a
nail is easily made red hot by a few wdl di-
rected blows of the hammer ; and by the friction
of solids, considerable increase of temperature
is produced ; thus the axle trees of carriages
sometimes inflame.

By strong pressure, fluids even are made lu-
minouSj as has been lately shewn by M. Des-
saignes.

When an elastic fluid is compressed by me-
chanical means, its temperature is raised, and
when the compressing forces are great and

t 9^ J

I'apidiy applied the effect is such as to cause the
ignition of bodies. A machine for setting fire
to tinder of the agaric, by the compression of
air, has been for some time in use.

When air is made to expand by removing
compressing forces, a diminution of tempera-
ture is occasioned. Thus the mercury in the
thermometer sinks at the time of the rarefac-
tion of air, by exhausting the receiver of an air
pump.

In the common language of chemistry, it
may be said that the capacity of elastic fluids
for heat is diminished by compression, and en-
creased by rarefaction ; and it is probable that
when the volumes of elastic fluids are changed
by change of temperature, there is likewise a
change of capacity, and on these ideas, it is easy
to account for the correspondence between the
diminution of the temperature of the atmos-
phere and its height ; for if it be conceived
that the capacity of air rarefied by heat, in-
creases as it ascends, the heat of temperature
which was the cause of its ascent, must, at a
certain elevation, become heat of capacity : and
the higher and more rarefied the air, the more
it is removed from the source of heat, and
the greater its power of diminishing tempera-
ture.

A very curious phenomenon is produced

t 91 1

during the action of the fountain of Hiero at
Schemnitz in Hungary ; the air in the machine
is compressed by a cohnnn oF water, 260 feet
high, and when a stop-cock is opened so as to
suffer air to escape, its sudden rarefaction
produces a degree of cold which not only
precipitates aqueous vapour, but causes it to
congeal in a shower of snow, and the pipe from
which the air issues, becomes covered with
icicles. Dr. Darwin has ingeniously explained
the production of snow on the tops of the high-
est mountains by the precipitation of vapour
from the rarefied air which ascends from plains
and valiies The Andes, placed almost under the
line, rises in the midst of burning sands ; about
the middle height is a pleasant and mild cli-
mate; the summits are covered with unchang-
ing snows .* and these ranges of temperature
are always distinct ; the hot winds from be-
low, if they ascend, become cooled in con-
sequence of expansion, and the cold air, if
by any force of the blast, it is driven down-
wards, is condensed, and rendered warmer as it
descends.

It seems probable that the capacity of solids
and fluids is increased by expansion, and di»
minished by condensation, and if this is the
case, the additions of equal quantities of heat
will give smaller increments of temperature at

I 92 ]

h'lgh than at low degrees, which must to a cer*
tain extent render the thermometer inaccurate
in the higher degrees, though prohably only to
a very small extent, of little importance as to
all practical purposes ; and this cause of inac-
curacy appears to be counteracted by another^
that fluids seem to be more expansible by heat
in proportion as their temperature is higher.

13. In all chemical changes there is an alter-
ation of temperature; and inmost instances
when gasses become fluids, or fluids solids,
there is an increase of temperature ; and vice
versa, there is usually a diminution of tem-
perature when solids become fluids, or fluids,
solids. For instance, when the highly inflam-
mable substance called phosphorus, the pro-
perties of which will be hereafter described, is
burnt in the air, it is found to condense a parti-
cular part of the air, and a high temperature is
produced during the process. When a solid
amalgam of bismuth, and a solid amalgam of
lead, substances which will be noticed in that
part of this work relating to the metallic com-
pounds, are mixed together, they become fluid,
and the thermometer sinks during the time of
their action.

There are, however, a number of cases in
which, though gaseous bodies or fluids are
formed from solids, an increase of temperature

[93],

occurs : thus, in the explosion of gunpowder a
large quantity of aeriform matter is disengaged,
yet a violent heat is produced.

And there is an instance in which at the
time of the separation of two species of gaseous
matter from each other, which is connected
with expansion, there is an increase of temper-
ature; thus, when a little of the gas whicli I
have named Euchlorine, and which consists of
the substance called by the French chemists
oxyrauriatic gas, and oxygene gas, is gently
heated in a small glass tube over mercury, an
explosion takes place, fire appears, and yet the
two gasses occupy a greater volume than before
the explosion.

14. As attempts have been made to account
for attraction, by the supposition of the exist-
ence of a peculiar matter, so calorific repulsion
has been accounted for by supposing a subiile
fluid, capable of combining v/ith bodies, and of
separating their parts from each other, which
has been named the mailer of heat, or caloric.

Many of the phenomena admit of a happy
explanation on this idea, such as the cold pro*
duced during the conversion of solids into
fluids or gassesj and the increase of temperature
connected with the condensation of gasses and
fluids ,• but there are other facts which are not
so easily reconciled to the opinion .- such are the

[ 94 ]

production of heat by friction and percussion ;-
and some of the chemical changes which have
been just referred to. When the temperature
of bodies are raised by friction, there seems to
be no diminution of their capacities, using the
word in its common sense ; and in many che-
mical changes connected with an increase of
temperature, there appears to be likewise an
increase of capacity. A piece of iron made red
hot by hammering cannot be strongly heated a
second time by the same means, unless it. has
been previously introduced into a fire. This
fact has been explained by supposing that the
fluid of heat has been pressed out of it, by the
percussion, which is recovered in the fire ; but
this is a very rude mechanical idea : the ar-
rangements of its parts are altered by hammer-
ing in this way, and it is rendered brittle. By
a moderate degree of friction, as it would appear
from Rumford's experiments, the same piece of
metal may be kept hot for any length of time ;
so that if heat be pressed out, the quantity must
be inexhaustible. When any body is cooled
it occupies a smaller volume than before: it is.
evident, therefore, that its parts must have ap-
proached towards each other : when the body
is expanded by heat, it is equally evident that
its parts must have separated from each oihen
The immediate cause of the phsenomena of heat

I 95 1

then is motion, and the laws of its communica-
tion are precisely the same as the laws of the
communication of motion.

Since all matter may be made to fill a smaller
volume by cooling, it is evident that the parti-
cles of matter must have space between them ;
and since every body can communicate the
power of expansion to a body of a lower tem-
perature, that is, can give an expansive motion
to its particles, it is a probable inference that its
own particles are possessed of motion ; bat as
there is no change in the position of its parts
as long as its temperature is uniform, the mo-
tion, if it exist, must be a vibratory or undulatory
motion, or a motion of the particles round their
axes, or a motion of particles round each other.

It seems possible to account for all the phas-
nomena of heat, if it be supposed that in solids
the particles are in a constant state of vibra-
tory motion, the particles of the hottest bodies
moving with the greatest velocity and through
the greatest space ; that in fluids and elastic
fluids, besides the vibratory motion, which must
be conceived greatest in the last, the particles
have a motion round their own axes, with diffe-
rent velocities, the particles of elastic fluids mov-
ing with the greatest quickness; and that in
etherial substances the particles move round
their own axes, and separate from each other^

[ 96 ]

penetrating in right lines through space. Tem-
perature maybe conceived to depend upon the
Velocities of the vibrations ; increase of capacity
on the motion being performed in greater space ;
and the diminution of temperature daring the
conversion of solids into fluids or o;asses, may
be explained on the idea of the loss of vibra-
tory motion, in consequence of the revolution
of particles round their axes, at the moment
when the body becomes fluid or triform, or
from the loss of rapidity of vibration in conse-
quence of the motion of the particles through
greater space

If a specific fluid of heat be admitted, it must
be supposed liable to most of the affections
which the particles of common matter are as-
sumed to possess, to account for the phaeno-
inena; such as losing its motion when combining
with bodies, producing motion when trans-
mitted from one body to another, andgaining
projectile motion, when passing into free space:
so that many hypotheses must be adopted to
account for its mode of agency, which renders
this view of the subject less simple than the
other. Very delicate experiments have been
made which shew that bodies when heated do
not increase in weight. This, as far as it goes,
is an evidence against a specific subtile elastic
fluid producing the calorific expansion ; but it

4

[9?]

cannot be considered as decisive, on account of
the imperfection of our instruments ; a cubical
inch of inflammable air requires a good balance
to ascertain that it has any sensible weight, and
a substance bearing the same relation to this,
that this bears to platinum, could not perhaps be
weighed by any methods in our possession.

Some arguments have been raised in favour
of the existence of a specific fluid of heat, from
the circumstances of the communication of heat
to bodies in exhausted receivers, and from the
manner in which they are affected by this heat;
but there are no means known in experimental
science of producing a perfect vacuum ; even
the best Torricellian vacuum must contain elas-
tic matter. The great capacity of such highly
rarefied matter is an obstacle to the indication of
temperature ; but supposing a communication
of heat, the laws must be analogous to those of
heat communicated to common air. If a long
cylinder of metal, placed perpendicularly, be
heated in the middle, the warmest part will be
above, from the ascent of heated particles of the
elastic medium ; but if a sphere be heated in
the middle, the hottest portion will be below,
as the heated elastic matter must remain lono-er
in contact with the inferior than with the supe-
rior portion.

The laws of the communication of heat, and
VOL. I. H,

[ 98 ]

the philosophy of its effects, are independent of
this speculative question, which will again be
considered, under new relations, in the part of
this work relating to the properties ethereal
or radiant matter.

IV. On chemical Attraction^ and the Laws of
Combination and Decomposition.

i. When olive oil and water are adtated to-
gether they refuse to act upon each other, and
separate according to the order of their densi-
ties, the oil swimming above the water. Oil
and water will not mix intimately ; they will
noi combine; and they are said to have no che-
mical attraction or ajfLnitf for each other. But
if oil and soap lees, or solution of potassa in
water, be mixed, the oil and the solution blend
together, and a species of soap will be formed,
which maybe procured as a soft solid substance
by evaporating a part of the water. This is an
instance of combination ; and solution of potassa
and oil are said to attract each other chemically,
or to have an affinity for each other.

2 Oil is almost insipid, but the solution of
potassa is a caustic substance, which corrodes
the skin, and has a strong taste. — The body
resulting from their union differs both from the
oil and the alkali in taste, smell, colour, and
in all its sensible qualities ; and it is a general

C 99 ]

GhsxRcter oi" chemical combination, that it chano-es
the sensible qualities of bodies.

Corrosive and pungent substances often be-
come mild and tasteless by their union, as is the
case with sulphuric acid and quicklime, which
form gypsum, or sulphate of lime.

Bodies possessed of little taste or smell often
gain these qualities in a high degree by combi-
nation. Thus sulphur, when inflamed ia oxy-
gene or in common air, dissolves and forms an
elastic fluid of a most penetrating and disagree-
able odour and peculiar flavour. The forms
of bodies, or their densities, likewise usually
alter ; solids become fluids, and solids and fluids
gasses, and gasses are often converted into fluids
or solids. Thus sugar, or salt, or isinglass, dis
solves in water. The consumption of charcoal
in our fires depends upon its uniting with a
part of the air, with which it forms an invisible
elastic fluid : mercury is rendered solid by being
heated with half its weight of tin, and a substance
of this kind is used for silvering mirrors. The gas
produced by the combustion of charcoal is con-
densed by another gas procured from quicklime
and sal ammoniac, when they are mixed over
mercury ; and the two invisible elastic fluids
form a white saline solid,

3. Many substances may be made to unite by
chemical affinity or attraction : thus common
, H2

f ]

salt, sugar, and pearl-ashes, will all dissolve
together in water. And the fosilalkali, sand
and the glass of lead, when melted toge-
ther, unite to form flint glass And in like
manner, porcelain is formed by heating together
mixtures of different earths. In a number of
the productions of nature likewise many sub-
Stances are combined into one mass or com-
pound. Thus many stones and gems are capable
of being resolved into several elements ; and in
the vegetable and animal kingdom there are
scarcely any compounds which do not contain
more than two principles, and complexity of
constitution seems uniformly connected with
organization.

4. That chemical attraction may be exerted
between bodies, it is necessary that they should
be brought into apparent contact. Thus no
body will act chemically upon another at any
sensible distance.

5. A freedom of motion in the parts of bodies,
or a want of cohesion, greatly assists combina-
tion ; and this circumstance is so marked, that
it was formerly considered as a chemical axiom,
which is still retained in some elementary books,
that bodies cannot act chemically on each other
unless one of tiiem be fluid or seriform. Such
an extensive general zation is, however, incqr-
regt ; thus crystalline munate of lime and snow.

0

C 101 ]

both cooled to 0° Fahrenheit act upon each other
ijnd liquify; and crystals ofoxalic acid and dry
lime treated in the same manner readily com-*
bine. The hardest arid the densest bodies,
however, vmdergo chemical chanties Avith the
greatest difficulty. Thus the sapphire in its
crystallized state, is not affected by boiling sul-
phuric acid ; but when in a fine pov/der, as alu*
mine, it is easily dissolved Minute division,
or solution, or fusion is necessary in almost all
chemical processes. In the chemical arts these
circumstances are always attended to ; and in
the phcenomena of external nature, the com-
mencement of chemical operations may in almost
all cases be traced to the agencies of fluids or
aeiif'orm substances. Thus in the bosom of our
rocks and mountains, where aic and water are
incapable of penetrating, all is permanent and
still, without change or motion; wherever wa-
ter and air are capable of acting, decomposition
slowly goes on ; and these agents gradually
change the nature of the surface, render liie soil
fertile, and decompose and degrade the exterior
of strata.

5. If equal weights of magnesia and of quick-
lime, in fine powder, and diluted aquaforiis or
nitric acid, be mixed together and suff red to
remain for some hours, it will be found by a mi-
nute examination, that a considerable part oi the

[102]

lime has been dissolved, but all the masnesia
will remain untouched. Hence, it is said, that
lime has a stronger altraclion for nitric acid,
than magnesia has.

This is proved likewise, by another experi-
ment of a different kind : it is easy to make a
solution of magnesia, in nitric acid, by heating
them together; and to make a solution of lime
in water, by agitating some powdered quick-
lime in distilled water. Let tlie solution of
lime be poured into the solution of magnesia,
a white powder or precipitate will separate, and
gradually fall to the bottom of the vessel in
which the mixture is made. This powder,
when examined, is found to be magnesia, and,
it is said, that magnesia is precipitated from
siitric acid, in consequence of the stronger
attraction of lime for that acid.

Ail bodies, that differ in their nature, com-
bine with different degrees of force ; and some
very important chemical phacnoraenain the arts
depend upon this circumstance. Thus the astrin-
gent 01 tanning substance, in the bark of trees,
which is soluble in water, is attracted from
water, by the prepared skins of animals, in con-
sequence of their stronger affinity Tor it, and
the skin, from being destructible by boiling
water, and decomposable, becomes indestruc-
tible and permanent. In like manner, indigo,

t ^03 ]

and other dyeing materials, are separated from
their soluiions, by vegetable or animal fibres,
and new combinations of ihem effected; and a
number of instances of the same kind mio-ht
be brought forward.

6. Different bodies unite with different de-
grees of force ; and hence, one body is capable
of separating others, from certain of their com-
binations ; and inconsequence of the same cir-
cumstance, mutual decomposilions of different
compounds take place. This has been called
double ajjinily^ or complex chemical attraction.
Thus, if an aqueous neutral solution of lime
and nitric acid, and a like solution of magnesia
and sulphuric acid, be mixed together, the
lime wiil quit the nitric acid, to unite to the
sulphuric acid, and the magnesia will leave the
sulphuric acid, to combine with the nitric acid.
The combination of nitric acid and magnesia,
will remain in solution; but the compound of
lime and sulphuric acid, being only slightly
soluble in water, will for the most part be pre-
cipitated, in the form of a white powder.

In many cases decompositions, that cannot
be produced by single attractions, may be
produced by double affinities. Thus the
elements of sulphate of baryta, or the c(»m-
bination of sulphuric acid, and the earth
called baryta, are so firmly united, that

[ 104 ]

no alkali, nor earth, will separate the acid from
the baryta. Potassa, which has a very strong
attraction for the acid, will not decompose it
alone ; but if potassa, combined with carbonic
acid, be digested for some time, with powdered
sulphate of baryta, there is a double decompo-
sition; and combinations of sulphuric acid and
potassa, and carbonic acid and baryta, are
formed.

7. If one part of pure oxygene gas, and two
parts of pure hydrogene gas, in volume, be
mixed together, in a glass tube, over mercury,
furnished with wires for passing the electrical
spark through it, and they be inflamed by the
electrical spark;* the gaseous matter will dis-
appear, and water will result. If two parts of
oxygene, be employed, and two of hydrogene,
one part of oxygene will remain ; in whatever
proportions they are mixed together, it is
found, that one of oxygene always condenses
two of hydrogene. It is evident then, that
oxygene and hydrogene, combine only in defin-
ite proportions, and that the water resulting is
always the same in its constitution.

If ^ piece of well burnt charcoal be introduced
into a vessel, two thirds filled with oxvo;ene
gas, over mercury; and the mercury be brought
to the same level on the inside and on the
* See Plate I. fig. 6.

[ 105 ]

outside of the jar, and the charcoal be inflamed
by a burning glass ;* there will be at first, ^n
expansion, but after the experiment is over, it
will be found, that the volume of the gas has
not perceptibly altered; and if the charcoal has
beeij in sufficient quantity, the whole of the
oxvp'ene will be found converted into carbonic
acid ; now the densities of oxygene gas and
carbonic acid gas, in whatever way they are
formed, are always the same ; and to each other,
as 34 to 47 nearly. It is evident then, that
carbonic acid must always contain the same
weight of oxygene and charcoal. If there is
twice as much oxygene in the vessel, as is ne-
cessary for the consumption of the charcoal,
half of it remains untouched ; and if the char-
coal is partly unconsumed, still the gas is the
same in quality; it always contains by weight,
5.7 of charcoal and 15 of oxygene.

There is an inflammable gas, called carbonic
oxide, which burns with a blue flame, and which
is obtained by igniting together zinc filings and
chalk. When two in volume of this gas, and
one in volume of oxygene, are acted upon by
an electric spark, over mercury, they inflame,
and there result exactly two volumes of car-
bonic acid gas ; there is no other product, and
the weight of the carbonic acid gas, exactly
* Plate II. fig. /.

[ 106 ]

equals the weight of the carbonic oxide and the
oxygene gas; so it is evident, that the carbo-
nic oxide contains exactly half as much oxygene
as carbonic acid, that is 5-7 of charcoal, require
7.5 of oxygene, to become carbonic oxide.
Again this is proved by decomposition : if elec-
trical sparks be passed through carbonic acid
gas, over mercury, it expands, and part of it is
decomposed, two volumes becoming two vo-
lumes of carbonic oxide, and one volume of
oxygene.

When the saltj called nitrate of ammonia, is
decomposed by heat, an elastic fluid is disen-
gaged, called nitrous oxide ; when one volume
of this gas, is mixed with one volume of hydro-
gene, and an electric spark is passed through
the mixture, inflammation takes place, water is
formed, and one volume of elastic matter remains,
which is azote. Now as one volume of hvdro-
gene takes half a volume of oxygene, lor its
conversion into water, it is evident, that this
gas, nitrous oxide, must be composed of two
in volume of azote, and one in volume of oxy-
gene, condensed into a space equal to two»

There is a gas produced by the solution
of copper in diluted nitric acid. If a little of
this gas be passed into a curved glass tube* over
mercury, and metallic arsenic be sublimed in
* Plate II. fig 8.

[ 107 ]

the gas, it is gradually decomposed. A solid
combination of arsenic and oxygene is formed,
which is found (if the weight of the azote re-
maining be compared with that of the nitrous
gas) to contain half a volume of oxygene, and
half a volume of gas remains, which is azote.
So it is evident, that as azote combined with one
proportion of oxygene gas, forms nitrous oxide,
so combined with two proportions, it forms
nitrous gas ; and one volume of nitrous gas
mixed over water with half a volume of oxy-
gene, is condensed, and forms a solution of
nitrous acid gas in water. So that this body
must consists of azote with, four proportions of
oxygene, nitrous oxide being considered as azote
with one proportion of oxygene ; and the quan-
tities in these bodies are always the same

It would be easy to bring forward a great col-
lection of evidences to shew, that in all compound
gaseous bodies, the quantities of the elements
are uniform for each species* and that when two

* That the proportions in compound gases are definite,
has long been generally acknowledged, but Mr. Higgins is, I
believe, the first person who conceived that when gasses com-
bined in more than one proportion, all the proportions of the
same element were equal; and he founded this idea, which
was made public in 1789, on the corpuscular hypothesis, that
bodies combine particle with particle, or one with two, or
three, or a greater number of particles. Mr. Dalton, about
1802, adopting a similar hypothesis, apparently without the
knowledge of what Mr. Higgins had written, extended his
views to compounds in general. Mr. Richter seem* to hav«

[ 108 ]

gaseous elements combine iri more than one pro-
portion, that the second or third proportion is
always a multiple, or a divisor of the first ; and
the case seems to be analogous with respect to
all true chemical compounds, whether solids or
fluids, in which no mechanical mixtures can be
suspected, and where no partial decompositions
can have taken place.

Thus if sulphuric acid be poured into any
solution of baryta, the solid precipitate of sul-
phate of baryta which falls down, is uniform
in its nature, and always contains about 34 of
acid, and 66 of baryta ; and the case is the same
with other similar compounds, and with neutral
salts in general.

And if tv»'o neutral salts mutually decompose

been the first person to shew that in the decomposition of
neutral salts by double affinity, the neutral state is preserved ;
and likewise that, when a metallic salt is decomposed by a
metal, all the oxygene and acid is transferred, and the metal
only changed, and that the new solution is as neutral, as the
former one. It had been ascertained, by different experiments,
that in certain cases when solids dissolved in gasses, the volume
is unchanged, and some instances of the combination of gasses
were kiicuvn, in which the volumes bore simple ratios to each
other, as in iiitioits Dxide, and water; but M. Gay Lussac is-
the first philosopher who attempted to generalize on the phe-
nomena, and shew that in all cases where gasses unite, it is
always in simple ratios of volume, 1 to l,or 1 to 2, or 1 to 3,
and that the condensation, if any, is in a simple ratio. His
very ir-geniou« ideus cn thib .subject, were made known towards
the close of liSOS. BerzeUns, in a work publishv d in 1810, has
determined ver) coi rci tij , s(/me of ihe definite proportions of
several important compounds. See Hi^gins's comparative View.

[ 109 ]

each other, in the interchange of principles,
there is never an excess of acid or of basis,*
and the resiiUing compounds are likewise per-
fectly neutral. Thus if 100 parts of nitrate of
baryta, which contain 41 nitric acid, and 59
baryta, be mixed with 67 of sulphat of potassa,
which consist of 30 of sulphuric acid, and 37
potassa, there will be found 89 of sulphate of
baryta, and 78 of nitrate of potassa ; so that 41
of nitric acid will combine with the 37 of potassa,
and 30 of sulphuric acid with the 59 of baryta.

It is evident from these circumstances, that
when one body has the power of detaching
another from its combinations, it will always
detach the same proportion. Thus from what-
ever basis baryta attracts sulphuric acid, it will
always detach the same quantity; and the same
quantity of potassa, from whatever acid it pre-
cipitates magnesia, will always throw down the
same proportion.

8. In cases when an alkaline substance com-
bines with more than one proportion of acid,
the same circumstances seem to occur as in

Dalton's new Chemical Fhilosophy. Richter Ueber die neuren
gegenstande der Chemie. Memoires d' Arcueil, T. ii. Bcr-
zelim Annales de Chemie, T. Ixvii. Thomson's system of Chemis-
try^ vol. Hi.

* M, M. Gay Lussac and Thenard, have lately stated, " that
in some mutual decorapositions of fluates, and muriates;
slightly acid solutions become alkaline; Recherches, T. ii.
page 28; but such changes must be complicated; and perhaps
a minute investigation may shew that they are not anomalous.

I no ]

the combinations of gaseous bodies. The pro-
portion is either a multiple or a divisor of the
first ; this is shewn by a very simple experiment,
first made by Dr. Wollaston : let a given weight
of the salt called carbonate of potassa, be thrown
into a tube over mercury, and diluted sulphuric
acid suflBcient to cover it be introduced into the
tube, a certain volume of carbonic acid gas will
be disengaged; let an equal weight of the salt
be heated to redness, when it becomes a subcar-
bonate, and let this subcarbonate be treated in
the same way, it will be found to give off exactly
half as much carbonic acid sas.

9. In the combination of solid and fluid sub-
stances which have not yet been decompounded,
with gasses, and in the union of compound
inflammable bodies with each other, and in all
mutual decompositions between bodies of this
class, similar circumstances appear to occur :
thus there are two combinations of mercury with
oxygene, the black and the red ; and one appears
to contain twice as much oxygene as the other.
There are two known combinations of iron with
oxygene, the black and the red oxide of iron ;
and the oxygene in the first being considered as
2, that in the second must be considered as 3,
that is 100 parts of iron take 29 parts of oxy-
gene to become the black oxide, and 43.5* to
become the red.

* These results I have obtained very nearly, namely, 29

[ 111 ]

The decompositions of compounds containing
oxymuriatic gas, or chlorine gas by water, afford
the best and most intelligible instances of double
decomposition. If equal volumes of light inflam-
mable air or hydrogene, and chlorine be mixed
together, and exposed to day-light, they slowly
act upon each other, no condensation takes place,
and they form an equal volume of muriatic acid
gas ; so that muriatic acid gas consists of hydro^
gene and chlorine in equal volumes ; and water, as
has been before stated, consists of two parts in
volume of hydrogene, and one part in volume
of oxygene. Now phosphorus and sulphur,
and most of the metals, combine with chlorine,
and form peculiar compounds, many of which
are decomposed by water, and the results are
phosphorus, sulphur, or the metals combined
with oxygene, and muriatic acid ; and the oxi-
dated compounds formed, are the same as those
produced in other ways; and it is evident,
that the quantity of hydrogene given to the
chlorine to form the acid, must be exactly in
the ratio of the oxygene added to the inflamma-
ble substance or the metal; thus phosphorus
burnt in chlorine in excess, forms a white
volatile substance, which 1 have named phos-
phor anee. When water is added to this, phos-

and 43 ; and they differ very little from those of Mr. Hassen-
fraiz, Dr. Thomson, and Mr. Beraelius.

{ 112 ]

phoric and muriatic acids are formed, and there
are no other products.

10. As in all well known compounds, the
proportions of the elements are in certain de-
finite ratios to each other ; it is evident, that
these ratios may be expressed by numbers ; and
if one number be employed to denote the
smallest quantity in which a body combines,
all other quantities of the same body will be
multiples of this number ; and the smallest
proportions in which the undecomposed
bodies enter into union being known, the
constitution of the compounds they form
may be learnt, and the element which unites
chemically in the smallest quantity being ex-
pressed by unity, all the other elements may be
represented by the relations of their quantities
to unity.

Hydrogene gas, or inflammable air is the
substance of which the smallest weights seem
to enter into combination ; and it appears to
exist in no definite compound in less pro-
portion than water. The specific gravity of
hydrogene is to that of oxygene as J 5 to I; and
as 2 volumes of hydrogene to 1 of oxygene
enter into the composition of water, the
raiio of the hydrogene in water will be to tlie
oxygene as 2 to 15 ; and it may be regarded as
composed of two proportions of hydrogene

[ 113 ]

and one of oxygene : and the number repre-
senting hydrogene will be 1, and that repre-
senting oxygene 15.

The weights of equal volumes of azote and
oxygene are to each other nearly as 13 to 15 ;
therefore supposing the number representing
the proportion, in which azote combines, gained
from the composition of nitrous oxide, which
contains two volumes of azote to one of oxy-
gene, it will be represented by 26 ; and nitrous
oxide will consist of two proportions of azote
equal to 26, and one proportion of oxygene,
equal to 15. Nitrous gas will consist of 1 of azote
and 2 of oxygene, 26 and 30. Nitrous acid gas
of I of azote and 4 of oxygene, 26 and 60.

Ammonia, which is decomposed by electri-
city into 3 volumes of hydrogene and 1 volume
of azote, will consist of 6 proportions of hydro-
gene and 1 proportion of azote, or 6 and 26.

The weight of chlorine or oxymuriatic gas^
is to that of hydrogene nearly as 33.5 to 1; and
muriatic acid gas consists of equal volumes of
these gases, and therefore is composed of 33,5
of chlorine, and 1 of hydrogene ; — but § of
chlorine may be made to combine with one of
oxygene in volume ; and double proportions of
this gas combine to form compounds, which
when decomposed by water, alford compounds
containing single proportions of oxygene, so that
the ratio of chlorine to oxygene, is that of 67

VOL. I. I

[ 114 ]

to 15, and the number representing chlorine is
correctly stated 67.

In like manner it is easy to deduce the num-
ber representing the other undecompounded
bodies ; and they will be found to correspond
as nearly as can be expected, in whatever way
they are obtained. Thus, whether the number
representing the proportion in which potas-
sium the basis of potassa combines, be gained
from its combination with oxygene or with
chlorine, the result will scarcely differ ; for 8
grains of potassium converted into the com-
pound of chlorine and potassium I have found
gain about 7.1 grains, and when converted into
potassa, they gain a grain and and as 7.1:8: :
67 : 75-4 ; and as . 1.6 : 8 : : 15 : 75, giving the
number representing potassium as about 75-

It is easy to form a series of proportional
numbers by taking of these numbers, on the
supposition that water is composed of one pro-
portion of hydrogene ahd one of oxygene ; but
in this case the number representing the pro-
portion in which oxygene combines must con-
tain a fraction ; and the calculations are much
expedited, and the formula rendered more
simple, by considering the smallest proportion
an integer.

Mr. Higgins has supposed that water is com-
posed of one particle of oxygene and one of
hydrogene, and Mr. Dalton, of an atom of each;
but in the doctrine of proportions derived from

[ M5 3

facts, it is not necessary to consider the combine*
ing bodies, either as composed of indivisible
particles, or even as always united, one and
one, or one and two, or one and three propor-
tions. Cases will hereafter be pointed out, in
which the ratios are very different ; and at pre-
sent, as we have no means whatever of judging
either of the relative numbers, figures, or
weights, of those particles of bodies which are
not in contact, our numerical expressions ought
to relate only to the results of experiments.

If it should hereafter be discovered, that any
of those substances now considered as undecom-
pounded, consist of other elements, these ele-
ments must be represented by some division of
their numbers ; and should even hydrogene be
found a compounded body, it would merely be
necessary to multiply all the numbers repre-
senting the other elements, by some common
number which would admit of a division into
proportions, representing the elements of hy-
drogene ; so that no discovery concerning the
composition of bodies, can interfere with the
general law of the definite nature of their com-
binations.

1 1. If the black oxide ofmanganese be exposed
to a strong heat, it gives oiBT oxygene gas, and
becomes brown ; but no heat as yet applied is ca-
pable of depriving it of the whole of its oxygene.

12

I 116 ]

Hence itis evident that when one proportion oF
one substance is combined with more than one
proportion of another, the first proportions may-
be separated with much more facility than the
last. There are numbers of other instances ; thus
the carbonate of soda, which contains two pro-
portions of carbonic acid to one of soda, gives off
half its carbonic acid with great facility, by heat,
but obstinately retains the other half. Nitric
acid is easily brought to the state of nitrous gas
by the abstraction of oxygene : nitrous gas with
more difficulty is converted into nitrous oxide,
but nitrous oxide is still less decomposable than
nitrous gas.

When one proportion of a body is combined
with two or more proportions of another, it
seems to enter with more difficulty into new
combinations, than when it is combined with
one proportion. Thus iron combined with two
proportions of sulphur in golden pyrites is not
acted upon by diluted sulphuric acid : but when
combined only with one proportion of sulphur,
as in the common artificial sulphuret, it is readily
acted upon.

It seems from these facts that two or more
proportions of one body attract a single pro-
portion of another body with more energy than
one proportion, and that two proportions or
mgre adhere to a single proportion with less

[ "7 ]

energy than one proportion ; or at least that a
second or a third proportion adheres with less
energy than the first.

It may possibly be said, that the effect of two
or three proportions, in defending one propor-
tion from the action of a new substance, may
depend upon mechanical causes, from their
more completely enveloping its parts ; but the
other solution of the effect seems to be the most
probable.

12. M. BerthoUet, to whom the first distinct
views of the relations of the force of attraction
to quantity are owing, has endeavoured to prove
that these relations are universal, and that elec-
tive affinities cannot strictly be said to exist.
He considers the powers of bodies to com ine as
depending in all cases upon their relative attrac-
tions, and upon their acting masses, whatever
these may be : and he conceives that in all cases
of decomposition, in wliich two bodies act upon
a third, that third is divided between them in
proportion to their relative affinities, and their
quantities of matter. Were this proposition
strictly correct, it is evident that there could be
scarcely any definite proportions : a salt crys-
tallizing in a strong alkaline solution, would be
strongly alkaline ; in a weak one less alkaline ;
and in an acid solution, it would be acid \ which
does not seem to be the case. In combina->.

I

[ 11' ]

tions, in which gaseous bodies are concerned,
the particles of which have perfect freedom of
motion, the proportions are unchangeable ; and
in all solid compounds, which have been accur-
ately examined, and in which there is no chance
of mechanical mixture, the same law s6ems to
hold good. It is certainly possible to dissolve
different bodies in fluid menstrua, in very
various proportions, but the result may be a
mixture of different solutions, rather than a
combination. M. Berthollet brings forward
glasses and alloys of metals, as compounds, con-
taining indefinite proportions ; but it is not
easy to prove, that in these, all the eletnents are
chemically combined ; and the points of fusion
of alkali, glass, and certain metallic oxides, are
so near each other, that transparent mixtures

of them may be formed. It cannot but be

supposed, that the attractive power of matter is
general, but in the formation of aggregates, cer-
tain arrangements seem to be always uniform.

IS- M. Berthollet conceives, that he has prov-
ed that a large quantity of a body having a weak
affinity, may separate a part of a second body,
from a small quantity of a third, for which it has a
strong affinity ; but even granting this, it does not
destroy the idea of definite proportions. Thus
in the fact, noticed by Bergman, the decompo-
sition of sulphate of potassa by nitric acid, one

[119]

proportion of potassa may be separated from the
acid ; and the other proportion may combine
with two proportions of acid ; phaenomena ana-
logous to those of common double affinity.

M. Berthollet states, that a large quantity ,of
potassa will separate a small quantity of sul-
phuric acid from sulphate of baryta ; but he
made his experiments in contact with the atmos-
phere, in which carbonic acid constantly floats ;
and carbonate of potassa and sulphate of baryta,
mutually decompose each other (6). Even
allowing the correctness of his views, still he
has not given a complete statement of facts.
If potassa separates sulphuric acid from baryta,
either there must exist an insoluble sulphate of
baryta, containing more baryta than the com-
mon sulphate, and which of course may contain
two proportions of baryta ; or baryta, sulphuric
acid, and potassa, must all be dissolved, in the
same fluid, which seems highly improbable.
M. Berthollet regards baryta as separable froiQ
sulphuric acid, by potassa ; but has not endea-
voured to shew in what form it appears after
the process.

14. M. Berthollet states, that soda is capable
ef separating a certain quantity of potassa from
sulphuric acid ; but, in his experiment, water was
present, as the soda must have been a hydrate ;
and he likewise used alcohol ; and thephseno-

I

[ 120 ]

menon may be a phaenomenon of double attrac-
tion, Potassa has a mucli stronger attraction
for water than soda ; and the soda may quit its
water, and the potassa its sulphuric acid ; and
the effect may be assisted by the stronger at-
traction of hydrate of potassa for alcohol.

In general, when large quantities of fluid or
fusible bodies, are used in experiments, the
attraction of the substances which are capable
of acting upon each other, is more readily
brought into play. In many solutions all the
elements are in chemical combination ; and
their separations depend not merely upon the
relative attractions of their parts, but likewise
on the manner in which they are acted on by
water ; and earths, and oxides, are usually
thrown down from their solutions in union with
water.

15. When an alkali precipitates an earth
from its solution in an acid, the earth, accord-
ing to M, Berthollet's ideas, ought to fall down
in combination with a portion of acid. But if
a solution of potassa be poured into a sulphuric
solution of magnesia, the precipitate produced,
after being well washed, affords no indication
of the presence of acid ; and M. Pfaff has shewn
by some very decisive experiments, that mag-
nesia has no action upon neutral combina-
tions of the alkalies and sulphuric acid ; and

[ 131 ]

likewise, that the tartaroiis acid is entirely se-
parated from lime, and the oxalic acid from
oxide of lead, by quantities of sulphuric acid,
merely sufficient to saturate the two bases ; and
these are distinct and simple instances of elective
attraction. Again, when one metal precipitates
another from an acid solution, the body that falls
down is usually free both from acid and oxy-
gene : thus zinc precipitates lead and tin, and
iron, copper ; and the whole of the oxygene
and the acid, is transferred from one metal to
the other.

16. M. Berthollet, in crystallizing sulphate
of potassa, from acid solutions, states that he
obtained salts, of which the first portion con-
tained 55.83 of acid in 100 parts, and another
portion only 49-5 ; but it is far from improba-
ble, that these salts were both mixtures of the
acidulous sulphate, and the neutral sulphate of
potash ; and the idea is strengthened by the
circumstance, that he obtained neutral sulphate
from the same solution, towards the end of the
process ; but even allowing the substances to
have been principally simple binary combina-
tions, and not mixtures, still the potassa and
the acid, may be regarded in them as in definite
proportions. The number representing potassa
being considered as 90, and that representing"
sulphuric acid as 75? the first may be conceived

[ 122 ]

to contain four of alkali and seven of acid, and'
the second, three of alkali and four of acid.

In cases in which solutions of salts are formed
in acid or alkaline menstrua, which are sup-
posed incapable of decomposing them, the re-
sults must be considered as depending upon a
new combination ; and in the evaporation of
the water or of the menstruum, and the crystal'
lization of the remaining constituents, the pro»-
portions, that have acted, will determine the
nature of the solids which are formed. There
appears no difficulty in reconciling the doctrine
of definite proportions, with the influence of
quantity ; none of the experiments of M. Ber-
thollet can be considered as strictly contra-
dictory to the doctrine, and some of the most
important results of this sagacious chemist afford
it confirmation.

17. M. Berthollet supposes that the attrac-
tions of bodies for each other, are inversely, as
the quantities that saturate. Thus, magnesia
and ammonia, take up more sulphuric acid than
equal quantities of potassa ; and therefore he
concludes, that magnesia and ammonia, have a
stronger attraction for acids than potassa: yet
potassa instantly separates magnesia and am-
monia from acids ; and though the facility with
which ammonia is expelled from a compound^
may be hypolhetically accounted for, by assum-

[ 123 ]

feig that the ease, with which it takes the gaseouS
state, assists its escape ; yet magnesia is in an
opposite case i and to account for chemical
changes, by supposing the effects of forms of
matter, which are about to appear, or powers not
in actual existence, such as elasticity or cohe-
sion, is merely the solution of one difficulty,
by the creation of another ; and ammonia, when,
solid or fluid, should require a new force to
render it elastic : and the cohesion, in a com-
pound, can only be regarded as the exertion of
the chemical attractions of its elements. The
action between the constituents of a compound
must be mutual ; sulphuric acid, there is every
reason to believe, has as much attraction for
baryta, as baryta for sulphuric acid : and
baryta is the alkaline substance, of which the
largest quantity is required to saturate sul-
phuric acid ; therefore, on M. Berthollet's view,
it has the weakest affinity for that acid ; but
less sulphuric acid saturates this substance, than
any other earthy or alkaline body ; therefore,
according to M. Berthollet, sulphuric acid has
a stronger affinity for baryta, than for any other
substance ; which is contradictory.

18. It cannot be laid down as a general law,
that the attractions of bodies are connected with
the weights of the proportions in which they
combine; yet in some cases the proportions.

[ m ]

which unite in the greatest quantity, or the
bodies represented by the highest numbers, are
separated by proportions combining in smaller
quantity, or by bodies represented by lower
numbers. Thus gold, pbtina, mercury, and
silver, are separated in their metallic states by
the common metals, which are represented by
much lower numbers, and the metallic oxides by
the alkalies ; but there are many exceptions;
and the intensity of attraction seems to be de-
pendent upon other causes, which are intimately
related to the electrical phaenomena, to be dis-
cussed in the next section.

19. The uniformity of the law of condensa-
tion, when gasses combine and form denser
gaseous compounds, in which the volume is
unaltered, or in which one of the elements is
condensed to or in which both are condensed
to ^, and the regularity of the forms of solid
bodies seem to depend entirely upon the con-
stancy of the nature of the combination, and
probably upon the corpuscular aggregates being
all of the same kind. If the particles of matter
be supposed to be globular, or to act in spheres
of attraction and repulsion, it would be easy
to account for their forms, by supposing a few
independent primary arrangements. Thus,
four particles may compose a tetrahedron, '
five, a tetraedral pyramid, six an octaedron,

C 125 ]

or a triedral prism, and eight, a cube or a
rhomboid.

20. It would be premature in this part of the
work, to enter upon any more minute views of
the laws of attraction, and the more refined
details will properly follow the history of the
agencies of different bodies on each other.

With respect to a power so constantly in
action, it is necessary, however, even at an early
period of the study, to possess some definite
ideas. If it be regarded as capricious in its
effects, and tending constantly to produce
different arrangements, chemistry would be
without a guide, without certain combinations,
and no results of analysis could be perfectly
alike; but fortunately for the progress of sci-
ence, this is not the case ; the changes of the
terrestrial cycle of events, like the arrangements
of the heavens, and the system of the planetary
motions, are characterized by uniformity and
simplicity ; weight and measure can be applied
to them, their order perceived, arid their laws
discovered.

VII. Of Electrical Attraction mid Repulsion,
and their Relations to Chemical Changes.

1. If a piece of dry silk be briskly rubbed
against a warm plate of polished flint glass, it
will be found to have acquired the property of

[ 126 ]

adhering to it, which it will retain for some
seconds ; if at the time this adhesive power
exists, the silk and glass be separated from each
other, they will both be found to have gained
the property of attracting very light substances,
such as the ashes of paper or fragments of gold
leaf; and the long filaments of the silk, if there
be any, will be seen to repel each other.

2. These bodies are said to be electrically
excited^ and the phsenomena are called electrical
phaenomena ; the peculiar circumstances under
which they occur, are best observed by the use
of an instrument called the electrical machine ;
it consists of a cylinder of glass* supported
upon glass pillars, and which can be made to
revolve, so as to press against a cushion of silk
rubbed over with a little amalgam of zinc and
mercury ; and of two cylinders of metal, one
in contact with the cushion, and the other op-
posite to the glass cylinder, both supported
upon glass.

g. If two gilt pith balls, suspended upon
strings of silk covered with tinsel, be hung upon
a wire, placed in contact with either of the me-
tallic cylinders, and the machine be put in
action, the balls will repel each other; but if
one ball be attached to a wire,, connected with
one metallic cylinder, and the other ball be
* Plate II. fig. %

[ 1" ]

attached to a wire connected with the other,
the two balls, when the machine is put into
action, will attract each other ; and at the mo-
ment that they come in contact, sparks of
light will be perceived, if the experiment be
made under favourable circumstances.

As the two balls, when in contact with the
same cylinder, may be considered as receiv-
ing the same impulse or impression, they are
said to be similarly eleclrijied; but -when in
contact with different cylinders, they are said
to be differently eleclrijied; and electrified bodies
that repel each other, are considered as in the
same electrical states ; those th?t attract each
other as in different electrical states.

4. There are probably no two bodies differ-
ing in nature, which are not capable of exhibit-
ing electrical phsenomena, either by contact,
pressure, or friction ; but the first substances in
which the property was observed, were vitreous
and resinous bodies ; and hence the different
states were called states of resinous and vitreous
electricity ; and resinous bodies bear the same
relation to flint glass, as silk. The terms, ne^p,'
tive and positive electricity, have been likewise
fidopted, on the idea, that the phaenomeija de-
pend upon a peculiar subtile fluid, which be-
comes in excess in the vitreous, and deficient in
the resinous bodies; and which is conceived

[ m ]

by its motion and transfer, to produce the elec-
trical phaenomena.

5. Flint glass and silk, silk and sulphur,
sulphur and metals, resin and metals, all by
friction or contact, become strongly electrical,
and of course attractive, and communicate their
attractive powers to small masses of matter
brought in contact with them ; a pith ball,
or a slip of gold leaf that has been touched
by flint glass, excited by silk, will be repelled
by a ball or slip that has been touched by silk
excited by sulphur, or by a ball or slip that has
been touched by sulphur excited by metals, so
that the attractive and repellent slates, depend
entirely upon the actions of the two substances,
and not upon any power peculiar to, and inhe-
rent in each.

6. It is upon this circumstance, that the elec-
trometer, which might be called the differeniial
one, is framed ; it consists of two gold leaves
attached to a metallic plate, and included in a
hollow cylinder of glass,* fixed upon another
metallic plate, which is connected with two
pieces of tin foil, pasted upon the glass oppo-
site to the leaves. When any electrified body is
made to touch the upper plate, the gold leaves
diverge ; if their divergence is increased by the
approach of flint glass excited by silk, they are

• Plate II. fig- 10,

[ 129 ]

said to have tlie same state as the glass, the
vitreous or the positive ; if their divergence is
diminished, they are said to be in the opposite
state, or to possess the resirlous or negative
electricity.

1. Wheri luminous phaenomena are connected
with electrical excitation, the different states
may be known by presenting a metallic point
to the excited body ; if rays of light Issue from
the point to the body, it is said to be negatively
electrified : but if the point appears simply
luminous, without sending off any rays, the
selectricity is said to be positive.

8. For measuring small degrees of electricity
of bodies, as compared with those of others of
the same kind, the eleclrical balance of Coulomb
is applied; it consists of a giJt pith ball, placed
upon a metallic rod, on the opposite extremity
of which is a thin leaf of metal ; *the rod is
suspended horizontally, by a fine metallic wire,
which passes into a glass tube, to the top of
which it is attached ; the glass tube is inserted
into a cylinder of glass, which contains a cop-
per ball, connected with a small bar of metal,
which is carried through an aperture in the
glass cylinder, into the atmosphere; a very
small force only is required to twiit the wire,
and when the two balls are brought in contact,
and the bar touched by the electrified body^

VOL. 1, K

[ 130 ]

thev gain the same kind of electricity, and re-
pel each other; and the degree of their repulsion
may be measured by a scale of degrees, made
on the circumference of the cylinder.*

9. Bodies receive the electrical influence in-
different manners. If a rod of glass be brought
in contact with any excited electrical body, it
will receive the electrical influence in the part
where it touched the body, and will be elec-
trical, to a little distance, round the point of
contact; but its remote parts will not be affected.
A rod of metal, on the contrary, suspended on
a rod of glass, and brouglit in contact with an
electrical surface, instantly becomes electrical
throughout. The glass, in common philoso-
phical language, is said to be a nonconductor of
electricity, or an substance; the metal

a conductor. Some bodies are affected to a much
greater extent than glass; but not nearly so
much as metals, such are animal and vegetable
substances, water, and fluids containing water ;
they are said to be imperfect conductors. Ac-
cording to the statements of Mr. Cavendish,
iron conducts 400 millions of times better than
water, sea water 100 times better than distilled
water, and water saturated with salt, 720 times
better. The mineral acids are the best fluid
conducting substances known, and after them, '
* Plate II. fig. 11.

[ 131 ]

saline solutions, the powers of which appear to
be nearly in proportion to the quantities oP
salts they coniain. Charcoal and metals, and
the greater number of inflammable metallic
compounds, are onduclors. Alcohol and ether^
are very imperfect conductors ; and sulphur^
oils, resinous substances, metallic oxides and
compounds of chlorine, nonconductors.

10. There is a stone found in many parts of
the world, called tourmaline, which is sometimes
crystallized as a nine-sided prism, terminated by
a three-sided and a six-sided pyramid ; when this
subbtance is gently heated, it becomes electrical,
and one extremity, that terminated by the six-
sided pyramid, is positive, the other is negative ;
to a certain extent, its electricities are exalted
by increasing the temperature ; when it begins
to cool, it is sdii found electrical; but the elec-
tricities are changed, the pyramid, before posi-
tive, is now negative, and vice versa. When
the stone is of considerable size, flashes of lig-ht
may be seen along its surface.

There are other gems and crystallized sub-
stances, which possess a property similar to that
of the tourmaline. The luminous appearance
of some diamonds, when heated, probably de-
pends upon their electrical excitation. The sub-
stance called the Boracite, which is a cube,
having its edges and angles defective, btcomes

K 2

[ 132 ]

electrical by heat, and in one variety presents
no less than eight sides, in different states, four
positive, four negative; ;ind the opposite poles
are in the direction of the axes of tlie crystal.

11. It would appear, that in all cases of elec-
trical action, the two electrical states are always
coincident, either in different parts of the same
body, or in two bodies ; and that they are always
equal, and capable of neutralizing each other.
If a connection be made by a wire, between the
positive and negative conductors of tlie elec-
trical machine, during the time of its action, all
electrical effects cease; and to produce a suc-
cession of effects, both conductors must be
brought near bodies connected with the ground,
which gain the opposite slate, in consequence of
what may be called induclion, and which will be
explained in the next paragraph.

12. When a nonconductor, or imperfect
conductor, provided it be a ihin plate of matter,
placed upon a conductor, is brought in con-
tact, with an excited electrical body; the surface,
opposite to that in contact, gains the opposite
electricity from that of the excited body ; and
if the plate be removed from the conductor and
the source of electricity, it is found to possess
two surfaces in opposite states. If a conductor
be brought into the neighbourhood of an ex-
iiited body, the air, which is ^ nonconductor,

[ 133 ]

being between them ; that extremity of the
conductor, which is opposite to the excited
body, gains the opposite electricity, and the
other extremity, if opposite to a body connected
with the ground, gains the same electricity, and
the middle point is not electrical at all. This
is easily proved, by examining the electricity
of three sets of gilt pith balls raised on wires
on the dilferent parts of the conductor, which
is thus affected by induced electricity.

If, instead of air, a plate of mica or glass be
between the two conductors, the same phaeno-
mena will occur ; so that it would appear that
the conductor merely gains two opposite elec-
tricities, or polar electricities, of the same kind
as those of the nonconductor. The phsenoraena
of sparks, of discharges, and of accumulated
electricity, depend upon this law. In the case of
the common electrical spark, a stratum of air is
charged in the same manner as a glass bottle,
partially coated with tin foil, is charged in the
Leyden experiment ; * when the hand is held
near the positive conductor of an electrical
machine, the person standing on the ground,
the hand is rendered negative, and the states
become exalted, till the polarities, as they may
l^e called, are annihilated through the air,
* Plate II. fig. 12.

[ 134 ]

producing a spark, a snap, and a distinct sensa-
tion. If a number of small pith balls, placed
upon a surface of metal, are caused to approach
an electrified body, they are brought into the
opposite state by induction, and are attracted
towards the body ; but when they come in
contact with it, this state is destroyed, they
gain the same state, and are repelled ; and if
they are properly placed, their alternate attrac-
tions and repulsions may be produced, as long
as the machine is in action.

13. If a number of cylinders of metal, iimi'
lated on glass, be placed in a line with each
other, but not in contact, and the last be con-
nected with the ground ;* when a powerfully elec-
trified conductor of a machine, is brought op-
posite to the first, they will all become electrical,
and every insulated cylinder will present two
poles ; the negative pole of one being opposite to
the positive pole of the other ; and if a spark is
produced by means of the last, sparks occur
throughout the whole arrangement. In like
manner a series of Leyden jars may be made to
charge each other, the outer surface of the first
renderins; neoiative the inner surface of the
second, and so on ; and by connecting the sur-
faces, that have the same kind of electricity, in,

* Plate III. fig. 13.

[ 135 ]

the first place, and then connecting two oppo-
site surfaces in the series, a powerful explosion*
may be produced.

14. When a point connected with the ground,
is brought near an electrified substance, it
rapidly gains the opposite state, and an imme-
diate discharge takes place, which continues till
the equilibrium is restored. Large surfaces are
electrified by induction much more slowly
than small ones, and are capable of accumulat-
ing much more electricity ; which renders the
discharge from them much more violent. In-
deed the electrical powers seem entirely to
belong to the surfaces of bodies, and not to be
connected with the quantity of solid matter
they contain.

15. It is in consequence of the principle of
induction, that the condensing electrometer is
so much more sensible than the common electro-
meter ; this instrument consists of two plates
of polished metal,-f the surfaces of which are
parallel, one connected with the plate of the
electrometer, the other moveable, in connexion
with the ground, and the plates are very near
each other. When the body supposed to be
electrical, is made to touch the top of the electro-
meter, and is afterwards removedj in separating
the plates, the effect will be perceived.

* Plate in. fig. 14. t Plate III. fig. 15.

[ 136 ]

16. The difference in what are called the
conducting powers of bodies, seems to de-
pend entirely upon the different manner in
which they receive the electrical polarities, or
in which their parts become capable of com-
municating attractive or repellent powers, to
other matter. Nonconductors appear to receive
polarities, only with great diSicultyj but retain
them for a long while, and present probably a
number of different alternations of poles, within
a small space, and cannot be effected to any
great distance. Imperfect conductors receive
polarity with more facility, but present fewer
alternations, and piieserve their electricities for
a shorter time. Perfect conductors are easily
affected throughout ; but present at most only
two poles, and the powers rapidly destroy each
other. The diflScuIty with which nonconduc-
tors receive polarity, is shewn in the phaeno.
mena of charging thick and thin coated plates
of glass and mica. The thin plates are capable
of being charged much more highly than the
thick ones, and the accumulation on the oppo-
site surfaces is much greater.

Rarefied air or gaseous matter, is much more
susceptible of receiving polarities, than dense
air or gaseous matter ; and hence, the electrical
spark will pass much further through rarefied
air or light gasses, than through dense air or

[ 137 3

heavy gasses ; it passes much further likewise
in gasses J than in nonconducting fluids.

17. If a nonconducting surface, coated with
two conducting surfaces, and charged so as to
give a spark of an inch in length, through air,
be connected by both its conducting surfaces,
with a similar apparatus not charged ; then both
systems piay be discharged together; but the
spark they will give, will be only half as long as
the single one would have given, if discharged
alone. The quantity of the electricity in this
Cc^se, is conceived not to be altered, but its
intensity, is said, to be only half as great when it
is discharged fron^ a double siirface ; and these
expressions of intensity and quantity, though
it is not easy to attach any very definite ideas
to them, are nevertheless useful, in giving more
facility to the arrangement of some important
electrical phsenomena.

18. When very small conducting surfacesare
used for conveying very large quantities of'elec-
tricity, they become ignited ; and of the different
conductors that have been compared, charcoal is
most easily heated by electrical discharges,* next
iron, platina, gold, then copper, and lastly zinc.
The phtcnomena of electrical ignition, whether

* The conclusions are drawn from experiments made by
^he electricity of the Voltaic apparatus.

[ 138 J

faking place in gaseous, fluid, or solid bodies,
always seem to be the result of a violent exertion;
ofthe electrical attractive and repellent powers,
which may be connected with molions ofthe par-
ticles of the substances affected. That no subtile
fluid, such as the matter of heat has been ima-
gined to be, can be discharged from these sub-
stances, in consequence of the effect ofthe eleC'
tricity, seems probable, from the circumstance,
that a wire of platina may be preserved in a state
of intense ignition in vacuo, by means of the
Voltaic apparatus, (an instrument which will
be immediately described), for an unlimitecT
time ; and such a wire cannot be supposed to
contain an inexhaustible quantity of subtile
matter.

19. Certain changes in the forms of sub-
stances, are always connected with electrical ef-
fects. Thus when vapour is formed or con-
densed, the bodies in contact with the vapour,
become electrical. IF, for instance, a plate
of metal, strongly heated, be placed upon
an electrometer, and a drop of water be poured
upon the plate, at the moment the water rises
in vapour, the gold leaves of the electrometer
diverge with negative electricity. Sulphur,,,
when melted, becomes strongly electrical dur-
ing the time of congelation ; and the case seems

I

[ 139 1

to be analo2;ous, with respect to nonconducting
substances in general, when they change their
forms.

20. As electricity appears to result from the-
general powers or agencies of matter, it is ob-
vious, that it must be continually exhibited in
nature, and that a number of important phseno-
mena must depend upon its operation. When
aqueous vapour is condensed, the clouds formed
are usually more or less electrical ; and the earth
below them being brought into an opposite state,
by induction, a discharge takes place when the
clouds approach within a certain distance, con*
stituting lightning ; and the undulation of the
air, produced by the discharge, is the cause of
thunder, which is more or less intense, and of
longer or shorter duration, according to the
quantity of air acted upon, and the distance of the
place, where the report is heard from the point
of the discharge. It may not be uninteresting
to ffive a further illustration of this idea; elec-
trical effects take place in no sensible time ; it
has been found, that a discharge through a cir-
cuit of four miles, is instantaneous ; but sound
moves at the rate of about twelve miles in a minute.
Now, supposing the lightning to pass through
a space of some miles, the explosion will be
first heard from the point of the air agitated,
jiearest to the spectator ; it will gradually come

[ 140 ]

from the more distant parts of the course of
the electricity, and last of all, will be heard
from the remote extremity ; and the different
degrees of the agitation of the air, and likewise
the difference of the distance, will account for
the different intensities of the sound, and its
apparent reverberations and changes.

21. In a violent thunder storm, when the
sound instantly succeeds the flash, the persons
who witness the circumstance, are in some dan-
ger; M'hen the interval is a quarter of a minute,
they are secure. In a thunder storm, the lowest
ground is the safest place, and a horizontal pos,-
ture, the least dangerous ; the neighbourhood
of trees, or buildings, should be avoided,, par-,
ticularly of trees, the living juices of which are
calculated to conduct the electricity, and make
part of a circuit. In a house, the cellars are
the safest places, and in a room the person
should stand as far as possible from the fire.
The means adopted by Franklin have, however,
to a great extent, averted the destructive effects
of atmospheric electricity; and by pointed
conductors, the thunder cloud is disarmed of
its terrors, and the lightning slowly discharged
in harmless corruscations.

If a school-boy's kite be mounted high in the
atmosphere, by means of a string, containing fila-,
i^ients of metal, fastened to a cowductor, fixed on.

[HI]

a glass rod; the conductor usually gives signs of
electricity, which will be greatest, when clouds
are floating in the atmosphere ; and it was by
means of a simple apparatus of this kind, that
the American Philosopher effected his grand
discovery of the identity of electricity and
lightning.

The water-spout is probably the result of
the operation of a weakly electrical cloud, at an
inconsidei able elevation above the sea,brou2;ht
into an opposite state : and the attraction of the
lower part of the cloud, for the surface of the
water, may be the immediate cause of this
extraordinary phenomenon.

The corruscations of the Aurora Borealis,
and Australis, precisely resemble strong artifi-
cial electricity, discharged through rare air;
and as the poles are nonconductors, being coated
with ice or snow, and as vapouf must be con»
stantly formed in the atmosphere above them ;
the idea of Franklin is not improbable, that
the Auroras may arise from a discharge of elec-
tricity, accumulated in the atmosphere near the
poles, into its rarer parts ; though other solu-
tions of the phsenomena may be given on the
idea, that the earili itself is endowed with elec-
trical polarity; or that the motions of the at-
mosphere produce the effect ; but all views on
this subject must be hypothetical, and the light

^ t 142 J

may result from other causes than electrical
action.

22. The common exhibition of electrical ef-
fects, is in attractions and repulsions, in which
masses of matter are concerned; but there are
other effects, in which the changes that take
place, operate in a manner, in small spaces of
lime imperceptible, and in which the effects are
produced upon the chemical arrangements of
bodies.

If a piece of zinc and a piece of copper be
brought in contact with each other, they will
form a weak electrical combination, of which
the zinc will be positive, the copper negative ;
this may be learnt by the use of a delicate con-
densing electrometer; or by pouring zinc filings
through boles, in a plate of copper, upon a
■common electrometer; but the power of the
combination may be most distinctly exhibited
in the experiments, called Galvanic experiments,
by connecting the two metals, which must be
in contact with each other, with a nerve and
muscle in the limb of an animal recently de-
prived of life, a frog for instance; at the mo-
ment the contact is completed, or the circuit
made, one metal touching the muscle, the otiier"
the nerve, violent contractions of the limb will
be occasioned. If a piece of zinc and copper,
in contact with each other in one point, b^j

placed in contact in other points with the sams
portion of water ; the zinc will corrode and
attract oxygene from the water, much more
rapidly than if it had not been in contact with
the copper; and if a small quantity of sulphuric
acid be added to the water, it will be seen that
globules of inOammable air are given off from
the copper, though it is not dissolved nor acted
upon.

23' The connection of chemical effects, with
the exhibition of electrical pov/ers, is however
best witnessed in combinations, in which these
powers, are accumulated by alternations of dif-
ferent metals and fluids. If plates of copper
and zinc two or three inches square, and pieces
of cloth of the same size soaked in a solution
of salt, or sal ammoniac, or nitre, be arranged in
the order of copper, zinc, moistened cloth, and
so on, and made into an insulated pile, of which
the series are 200 f several remarkable pheno-
mena will occur.

When one hand is applied to the bottom
of the pile, and the other to the top, both
hands being moistened, a shock will be per-
ceived.

When a metallic wire, having a bit of well
burned charcoal at its extremity, is made to con-
nect the two extremities of the pile, a spark will
• See Plate III. fig. 15, l6.

[ 144 ]

he percdved, or the point of Uie charcoal will
become ignited.

A wire connected with the top of the jsile,
brought in contact with a sensible electrometer,
will cause theleaves to diverge ; and by removing
the wire and applying excited glass to the elec-
trometer, it will be found that the electricity is
positive ; a wire connected with the bottom of
the pile will affect it with negative electricity *
a wire from the middle of the pile will have no
influence on the instrument.

If wires of platina from the extremities of the
pile be introduced into water, or into two pot"-
tiorls of water connected by moist substances,
oxygene gas vv^ill separate at the wire exhibiting
the positive electricity, and hydrogene gas at the
wire exhibiting the negative electricity; and th^
proportions are such, when the proper circurri-
stances existj that they will produce water when
exploded by the electrical spark, that is, the
volume of hydrogene will be to that of oxygene^
as two to one.

If the same wires be introduced into a strong
solution of sulphuric or phosphoric acid, or into
metallic solutions, oxygene will separate at the
positive surface, the inflammable or metallic
matter contained in the solution, at the negative
surface.

When any substance rendered fluid by heat^

[ 145 ]

■consisting of water, oxygene and inflammable
or metallic matter, is exposed to those wires,
similar phseoomeoa occur.

When any solution of a neutral salt contain-
ing acid, united to alkaline, earthy, or common
metallic matter, is used ; besides the other phae-
nomena that take place, acid matter collects
round the positively electrified surface; alkali,
earth, or oxide, round the negative surface ; and
if two separate vessels are employed to contain
the solution, connected by moist asbestus, it is-
found, that the acid collected in the vessel con-
taining the wire, positively electrified, will be
in definite proportion to the matter collectedin
the other cup ; that is, it will form with it a
neutrosaline compound.

If a solution of muriatic acid in water, be
acted on by the wires, hydrogene will separate
at the negative surface, and chlorine or oxy-
muriatic gas, at the positive surface.

24. This apparatus, which exhibits in so
distinct a manner the relations of electrical
polarities to chemical attractions, is the graijd
invention of Volta, made known in the first
year of this century; its electrical effects have
been long known, but the phsenomena of its
operation in decomposing bodies, are of n^rie
recent discovery.

Several modes of constructing it have been

VOL. I, L

[ 146 ]

adopted, some of which are much superior ia
point of convenience, to that which has been just
described.

One mode is by^ soldering the plates of zinc
and copper together, and by cementing them
into troughs of baked wood, covered with ce-
ment, in the regular order, so as to form cells
to be filled with the fluid menstruum; each
surface of zinc being opposite to a surface of
copper; and this combination is very simple
and easy of application.

Another form is that of introducing plates of
copper and of zinc, fastened together by a slip
of copper, into a trough of porcelain contain-
ing a number of cells corresponding to the
number of the series. The different series may
be introduced separately into the troughs, and
taken out without the necessity of changing the
fluid, or they may be attached to a piece of
baked wood (and when the number is not very
large) introduced into the cells, or taken out
together.*

25' Similar polar electrical arrangements to
those formed by zinc and copper, may be
made by various alternations of conducting
and imperfect . conducting substances; but for
the accumulation of the power, the series must
€onsiist of three substances or more, and

•■- • ■ : - ^ » -Plate IIL fig. IT-

[147]

one at least must be a conductor. Silver or.
copper when brought in contact with a solu-
tion of a compound of solphur and potassa, at
one extremity, and in contact with water or a
solution of nitric acid, at the other extremity,
some saline solution being between the sulphu-
retted and the acid solutions, forms an element
of a powerful combination, which will give
shocks when fifty are put together ; the order
is copper, cloth of the same size moistened with
solution of nitric acid, cloth moistened in solu-
tion of common salt, cloth moistened in solu-
tion of the compound of sulphur, copper, and
so on; the specific gravities of the solutions •
should be in the order in which they are ar-
ranged, to prevent the mixture of the acid and
sulphuretted solution ; that is, the heaviest so-
lution should be placed lowest.

The tables annexed contain some series, which
form Voltaic electrical combinations, arranged
in the order of their powers ; the substance
most active beins; named first in each column.

A

[ 148 ]

Table of some Electrical Arrangements, ivhich by
Combination form Voltaic Batteries, composed of
two Conductors and one imperfect Conductor.

Zinc

Each of the^e is the

Solutions of nitric acid

Iron

positive pole to all the

of muriatic acid

Tin

metals below it, and

of sulphuric acid

Lead

negative with respect

of sal-ammoniac

Copper
Silver

to the metals above it

of nitre

in the column.

other neutral salts

Gold

Platina

Charcoal

I'able of some Electrical Arrangements , consisting
of one Conductor and two imperfect Conductors.

Solution of sulphur and potash

Copper

Nitric acid

of potash

Silver

Sulphuric acid

of soda

Lead

Muriatic acid

Tin

Any solutions

Zinc

containing acid

other motals

Charc( al

The metals having the strongest attraction
for oxygene, are the metals which form the
positive pole, in all cases in which the fluid
menstrua act chemically by affording oxygene ;
but when the fluid menstrua affrjrd sulphur to
the metals, the metal having; the strongest at'
traction for sulphur under the existing circum-
stances, determines the positive pole ; thus in a
series of copper and iron, introduced inio a por-
celain trough, the cells of which are filled with
water or with acid solutionSj the iron is positive,

[ 149 ]

and the copper negative; but when the cells are
filled with solution of sulphur and potash, the
copper is positive and the iron negative.

In all coiTibinations in which one metal is
concerned, the surface opposite the acid, is ne-
gative, that in contact with solution of alkali
and sulphur, or of alkali, is positive.

26. The energy of a combination to give re-
pulsive or attractive powers to masses of matter
or to affect the electrometer, seems to increase
with the number of the series, as does the power
to give shocks, and to decompose bodies ; but
as long as the surface of the gold leaves in the
electrometer, or of the human body, or of the
water acted upon, is the same, and less than that
of the acting plates, increase of surface of the
plates is connected with no increase of power.
In the operation upon metallic substances or
charcoal, or upon good imperfect conductors, the
case, however, is different. Thus, though a bat-
tery composed of plates of copper and zinc a foot
square, will not affect the condensing electro-
meter more, nor decompose more water, nor
give greater shocks to the fingers, than a battery
containing plates of an inch square, yet it will
ignite more than 100 times as much fine platina
wire, and decompose sulphuric acid, and the
water in strong saline solutions with infinitely
more rapidity. This has been expressed by

[ 150 ]

Mr. Cavendish in the statement, that the inten-
sity is the same in both cases ; but that the
quantity is in some ratio as the surface. The
quantity in the small plates is as much or more
than such imperfect conductors as water and
the human body can carry off by a small sur-
face; whilst better conductors can transmit
the whole quantity afforded by the large plates,
even when used in very thin laminae or wires.
The correctness of this view may be shewn by
a very simple experiment. Let two platina
wires, from the extremities of a battery com-
posed of plates of a foot square, be plunged into
water, the quantity of gas disengaged from the
wires will be nearly the same as from an equal
number of plates of an inch square ; let the fin-
gers of each hand, moistened with water, be
applied to the two extremities of the battery, a
shock will be perceived nearly the same as if
there had been no connection between the wires
and the water. Whilst the circuit exists through
the human body and through water, let a wire
attached to a thin slip of charcoal be made
to connect the two poles of the battery, the
charcoal will become vividly ignited. The wa-
ter and the animal substance discharge the elec-
tricity of a surface, probably not superior to
their own surface of contact with the metals ;
the wires discharge all the residual electricity

r ]

of the plates; and if a similar expeiiment be
made on plates of an inch square, there will
scarcely be any sensation, when the hands are
made to connect the ends of the battery, a
circuit being previously made through water ;
and no spark when charcoal is made the me-
dium of connection, imperfect conductors hav-
ing been previously applied.

The first distinct experiment upon the igni-
ting powers of large plates was performed by
M, M. Fourcroy, Vauquelin, and Thenard. But
the grandest combination ever constructed for
exhibiting the effects of extensive surface, was
made by Mr. Children: it consists of twenty
double plates four feet by two ; of which the
whole surfaces are exposed, in a wooden
trough, in cells covered with cement, to the
action of diluted acids. This battery, when
in full action, had no more effect on water
or on the human body than one containing
an equal number of small plates; but when
the circuit was made through metallic wires,
the phsenomena were of the most brilliant
kind. A platina wire of one thirtieth of an
inch in thickness, and eighteen inches long,
placed in the circuit between bars of copper,
instantly became red hot, then white hot, the
brilliancy of the light was soon insupportable
to the eye, and in a few seconds the metal fell

[ 152 ]

fused into globules. The other metals were
easily fused or dissipated in vapour by this
power. Points of charcoal ignited by it pro-
duced a light so vivid; that even the sunshine
ciDmpared with it appeared feeble.

Mr. Children has another battery in con-
struction, the plates of which are double the size
of that just described, and which are to be ar-
ranged in pairs in single troughs, and connected
by means of plates of lead in regular order.

27. The most pov/erful combination that exists
in which number of alternations is combined
with extent of surface, is that constructed by the
subscriptions of a few zealous cultivators and pa-
trons of science, in the laboratory of theRoyal In-
stitution. It consists of two hundred instruments,
connected together in regular order, each
composed often double plates arranged in cells
of porcelain, and containing in each plate thirty-
two square inches ; so that the whole number
of double plates is 2000, and the whole surface
128000 square inches. This battery, when the
cells were filled with 60 parts of water mixed
with one part of nitric acid, and one part of sul-
phuric acid, afforded a series of brilliant and
impressive effects. When pieces of charcoal
about an inch long and one sixth of an inch in
diameter, were brought near each other (within
the thirtieth or fortieth part of an inch,) a bright

[ 153 ]

spark was produced, and more than half the
volume of the charcoal became ignited to white-
ness, and by withdrawing the points from each
other a constant discharge took place through
the heated air, in a space equal at least to four
inches, producing a most brilliant ascending
arch of light, broad, and conical in form in the
middle.* When any substance was introduced
into this arch, it instantly became ignited ; pla-
tina melted as readily in it as wax in the
flame of a common candle ; quartz, the sap-
phire, magnesia, lime, all entered into fusion ;
fragments of diamond, and points of char-
coal and plumbago, rapidly disappeared, and
seemed to evaporate in it, even when the con-
nection was made in a receiver exhausted by the
air pump ; but there was no evidence of their
having previously undergone fusion.

When the communication between the points
positively and negatively electrified was made
in air, rarefied in the receiver of the air pump,
the distance at which the discharge took place
increased as the exhaustion was made, and
when the atmosphere in the vessel supported
only one fourth of an inch of mercury in the
barometrical gage, the sparks passed through
a space of nearly half an inch ; and by with-
drawing the points from each other, the dis-
charge was made through six or seven inches,
* Plate III. fig. 18.

t 154 ]

producing a most beautiful corruscation of pur-
ple light, the charcoal became intensely ignited,
aild some platina wire attached to it, fused with
brilliant scintillations, and fell in large globules
upon the plate of the pump. All the phaeno-
mena of chemical decomposition were produced
with intense rapidity by this combination. When
the points of charcoal were brought near eacK.
other in nonconducting fluids, such as oils,
ether, and oxymuriatic compounds, brilliant
sparks occurred, and elastic matter was rapidly
generated ; and such was the intensity of the
electricity, that sparks were produced, even in
good imperfect conductors, such as the nitric
and sulphuric acids.

When the two conductors from the ends of
the combination were connected with a Leyden
battery, one with the internal, the other with
the external coating, the battery instantly be-
came charged, and on removing the wires, and
making the proper connections, either a shock
or a spark could be perceived ; and the least
possible time of contact was sufficient to renew
the charge to its full intensity.

28. The general facts of the connection of
the increase of the different powers of the bat-
tery with the increase of the number and sur-
face of the series, are very distinct ; but to de-
termine the exact ratio of the connection is a
problem not easy of solution.

[ 155 3

M. M. Gay Lussac and Thenard have an-
nounced, that the power of chemical decompo-
sition increases only as the cube root of the
number of plates ; but their experiments were
made with parts of piles of a construction very
unfavourable for gaining accurate results ; and
in various trials made witli great care in the
laboratory of the Royal Institution, the results
were altogether different. The batteries em-
ployed were parts of the great combination,
carefully insulated, and similarly charged ; arcs
of "zinc and silver presenting equal surfaces, and
arranged in equal glasses filled with the same
kind of fluid, were likewise used ; and the
tubes for collecting the gasses were precisely
similar, and filled with the same solution of
potassa.* In these experiments ten pairs of plates
produced fifteen measures of gas : twenty pairs
in the same time produced forty nine : again,
ten pairs produced five measures ; forty pairs in
the same time produced seventy-eight measures.
In experiments made with arcs, and which ap-
peared unexceptionable, four pairs produced
one measure of gas ; twelve pairs in the same
time produced nine and of gas : six pairs
produced one measure of gas ; thirty pairs,
under like circumstances, produced 24-5 rnea-

«- Plate IV. fig. 19.

[156]

sures ; and these quantities are nearly as the
squares of the numbers,

. It would appear from the experiments of
Vanmarum and Pfaff, confirmed by those of
Messrs. Wilkinson, Cuthbertson, and Singer,
that the increase of power of batteries, the
plates of which have equal surfaces, is as the
number. I found that ten double plates, each
having a surface of a hundred square inches,
ignited two inches of platina in wire of one
eightieth of an inch ; twenty plates, live inches ;
forty plates, eleven inches ; but the results of
experiments on higher numbers were not sa-
tisfactory ; for one hundred double plates of
thirty-two square inches each, ignited three
inches of platina wire of one seventieth, and
one thousand ignited only thirteen inches, and
the charges of diluted acid were similar in both
cases.

The power of ignition for equal numbers of
plates, seems to increase in a veiy high ratio
with the increase of surface, probably higher
than even the square ; for twenty double plates,
containing each two square feet did not ignite
one sixteenth as much wire as twenty, con-
taining each eight square feet, the acid em-
ployed being of the same strength in both
cases.

[ 157 1

Numerous circumstances are. opposed to the
accuracy of experiments made with high num-
bers, or very large surfaces; the activity of com-
binations rapidly diminishes in consequence of
the decomposition of the menstruum used ; and
this decomposition is much more violent, the
greater the number and surface of the alterna-
tions ; the vapour rising likewise, when the ac-
tion is intense, interferes by its conducting
power, and the gas by its want of conducting
power ; and when series containing above five
hundred double plates are used, unless the in-
sulation is very perfect, there is a considerable
loss of electricity ; thus the great battery of two
thousand double plates belonging to the Royal
Institution, will scarcely act by its true poles,
when arranged on a floor of stone, and requires
not merely the insulation of porcelain, but
likewise of dry wood ; and when arranged on
a stone floor, it is hardly possible to walk near
any of the approaching series without receiving
shocks. In cases of the ignition of wire, the
cooling influence of the substances in contact,
and of that part of the chain not ignited, inter-
feres most, when small quantities of wire are
employed and with feeble powers; and hence the
effect is at first in a lower and then in a higher
ratio than the number, when the whole ranaie
is small, as in the experiments above stated. If

[ 158 ]

there is an imperfect connection in any of the
series, a great diminution of power is the conse-
quence. If one plate is corroded, or covered with
more oxide than the rest, there is a general loss
of effect. If copper is substituted for zinc, or zinc
for copper, in a single series, the result is similar ;
and I find that a platina wire, introduced in the
place of an arc of silver and zinc, in a series of
thirty, diminished its power of producing gas so
much, that it was equal only to that of four.

Q9. The circumstance most important in
electricity, perhaps, is its connection with the
chemical powers of matter, and the manner in
which it modifies, exalts, or destroys these
powers. Most of the substances that act dis-
tinctly upon each other electrically, are likewise
such as act chemically, when their particles have
freedom of motion; this is the case with the
different metals, with sulphur and the metals,
with acid and alkaline substances ; and the rela
tions of bodies are uniform ; those that have the
highest attracting powers being in the relation
of positive^ in arrangements in which chemical
changes can go on. Thus, as is shown in the
tables, page I48, zinc is positive with respect to
iron, iron with respect to copper, copper with
respect to silver, and so on in all combinations
in which oxygcne is capable of being combined
with the metal; but copper is positive \vith

[ 159 }

respect to iron in compoimd menstrua contain-
ing sulphur ; the electrical power being in all
eases apparently connected with the power of
chemical combination.

Crystals of oxalic acid touched by dry quick-
lime exhibit electrical powers; and the acid is
negative, the lime positive.

All the acid crystals, upon which I have
experimented when touched by a plate of
metal, render it positive. And in Voltaic com-
binations with single plates or arcs of metal, as
is stated in page 149, the metal is negative on
the side opposed to the acid, and positive on
the side or pole opposed to the alkali.

Bodies that exhibit electrical effects previous
to their chemical action on each other, lose
this power during combination. Thus, if a
polished plate of zinc is made to touch a
surface of dry mercury, and quickly sepa-
rated, it is found positively electrical, and the
effect is increased by heat ; but if it be so heated
as to amalgamate with the surface of the mer-
cury, it no longer exhibits any marks of elec-
tricity. The case is analogous with copper
and sulphur ; and iron acts more powerfully
than zinc with quicksilver in a permanent elec-
trical combination, as in the experiments of
Colonel Haldane ; apparently, because under,
common circumstances it is incapable of amal-
gamating with that metal. When any conduct-

[ 160 ]

ing substance, capable of combining with oxy-
gene, has its positive electricity increased, it
will attract oxygene with more energy from
any imperfect conducting medium ; and metal-
lic bodies that in- their common state have no
action upon water, such as silver, attract oxy-
gene from it easily, when connected with the
positive pole in the Voltaic circuit; and bodies
that act upon water, such as zinc and iron,
so as to decompose it slowly, refuse to attract
oxygene from it when they are negatively elec-
trified in the Voltaic circuit.

Acids, which are negative with respect to
alkalies, metals, and earths, are separated from
these bodies in the Voltaic circuit at the
positive surface ; and alkalies, metals, and
earths, are separated from acids at the negative
surface : and such are the attracting powers of
these surfaces, that acids are transferred through
alkaline solutions, and alkalies through acid
solutions, to the surfaces where they have their
points of rest. It is easy to shew this by making
a combination of three agate cups,* one con-
taining sulphate of potassa, one weak nitric
acid, and the third distilled water, and connect-
ing them by asbestus moistened in pure water,
in such a manner, that the surface of the acid
is lower than the surface of the fluid in the
* Plate IV. fig. 20.

[161]

©ther two cups. When two wires of platlna
from a powerful Voltaic apparatus are intro-
duced into the two extreme cups, the solution
of the salt being positively electrified, a decom-
position will take place, and in a certain time a
portion of potassa will be found dissolved in
the cup in contact with the negative wire,
though the fluid in the middle cup will still be
sensibly acid.

30. Such are the decomposing powers of
electricity, that not even insoluble compounds
are capable of resisting their energy ; for even
glass, sulphate of baryta, fluor spar, 8cc. when
moistened and placed in contact with elec-
trified surfaces from the Voltaic apparatus, are
slowly acted upon, and the alkaline, earthy, or
acid matter carried to the poles in the common
order. Not even the most solid aggregates, nor
the firmest compounds, are capable of resisting
this mode of attack ; its operation is ^low, but
the results are certain ; and sooner or later, by
means of it, bodies are resolved into simpler
forms of matter.

31. It is in consequence of the phaenomena
of electrical decomposition, in which metals,
inflammable bodies, alkalies, earths and oxides,
are determined to the negative surface, and
oxygene, chlorine, and acids to the positive sur-
face, thai for some time it was conqeived, that

VOL. I. M

[ 162 ]

various substances, might be composed from
pure water, by means of electricity, st ch as
potassa, soda, and muriatic acid. A strict inves-
tigation of the circumstances under which these
substances appeared, led me to discover that
they were always furnished from the vessels, or
from impurities in the water, and enabled me to
determine the general principles of electrical
decomposition, and to apply this power to the
resolution of some species of matter, of unknown
nature, into their elements.

32. The connection of electrical pbaenomena
and chemical changes is evident likewise in the
general phsenomena of the battery. The most
powerful Voltaic combinations are formed by
substances that act chemically with most energy
upon each other ; and such substances as undergo
no chemical changes in the combination, fe;shibit
no electrical powers. Thus zinc, copper, and ni-
tric acid form a powerful battery ; whilst silver,
gold, and water, which do not act chemically on
each other, in series of the-same number, produce
no sensible effect. These circumstances led some
philosophers to suppose, at an early period of the
investigation of the electrical powers of metals,
that they were entirely the result of chemical
changes : that as heat was produced by this
action, when exerted under common circum-
stances, so electricity resulted from it under

[ 163 ]

other circumstances ; and many of the phaeno-
mena were conformable to such an idea, and
some ingenious enquirers adopted it to such an
extent, as to suppose electricity in all cases
owing to this cause.

This generalization, whether applied to Vol-
taic or to common electricity, seems, however,
to be incorrect. Zinc and copper, as has been
stated, diffefent metals and oxalic acid, diffe-
rent metals and sulphur, or charcoal, exhibit
electrical effects after mere contact, and that in
cases when not the slightest chemical change can
be observed ; and if in these experiments chemi-
cal pha:nomena are produced by the action of
menstrua, all electrical effects immediately cease:
and if is not philosophical to assume a cause
to account for an effect, when no such cause can
be perceived.

It has been supposed that the action of
the common electrical machine depends upon
the oxidation of the amalgam ; but I found by
mounting a small machine in a glass vessel, in
such a manner that it could be made to revolve
in any species of gas, that it was active in hy-
drogene gas, and more active in carbonic acid
gas than in the atmosphere (probably owing to
its greater density). The experiment has been
several times repeated under different circum-
stasoGes, and uniformly with the same results ;

M S

[ 164 ]

and may be regarded as decisive in this im-
portant question.

33- Electrical effects are exhibited by the same
bodies, when acting as masses, which produce
chemical phaenomena when acting by their par-
ticles ; it is not therefore improbable, that the
primary cause of both may be the same, and
that the same arrangements of matter, or the
same attractive powers, which place bodies in
the relations of positive and negative, i. e. which
render them attractive of each other electrically,
and capable of communicating attractive powers
to other matter, may likewise render their par-
ticles attractive, and enable them to combine,
when they have full freedom of motion.

It is not a little in favour of this hypothesis,
that heat, and sometimes heat and light, result
from the exertion of both electrical and che-
mical attractive powers ; and that by rendering
bodies, which on contact are in the relation of
positive to othersj still more highly positive,
as has been stated, page 160, their powers of
combination are increased ; whereas, when they
are placed in a state corresponding to the nega-
tive electrical state, their powers of union are
destroyed. That acids can be detached from
alkalies, oxygene and chlorine from inflammable
matter by metallic substances, or by a fluid men-
struum highly positive, is likewise favourable
to the supposition.

[ 165 ]

$4' This view of the possibility of the de-
pendance of electrical and chemical action upon
the same cause, has been much misrepresented.
It has been supposed that the idea was enter-
tained, that chemical changes were occasioned
by electrical changes ; than which nothing is
further from the hypothesis, which I have ven-
tured to advance. They are conceived, on the
contrary, to be distinct phaenomena ; but pro-
duced by the same power, acting inone case on
masses, in the other case on particles. The hy-
pothesis has been attempted to be controverted
by experiments which are far from satisfactory,
and some of which have no connection with it.
It has been said that acids rendered positive
by the common machine, will still combine
with alkalies, and that other contradictory re-
sults may be obtained ; but a non-conducting
acid, though brought in contact with a positive
surface, electrified by the common machine, is
not rendered positive throughout ; but gains
a polar electricity, which extends only to a
certain depth into the crystals, and the ex-
terior surface, if electrical at all, is negative:
and if a wire, positively electrified by the
common machine, be introduced into an acid
solution, this solution, if at all affected, when
made to act upon another solution, will be ne-
gative at its point of action ; that is, it will be

[ 166 ]

positive near the wire, but will be in the oppo-
site state with regard to another surface. And
eommon electricity is too small in quaistity, in its
usual form of application, to influence chemical
changes ; for it requires a very strong machine
acting upon a very small surface, to produce
any sensible polar decompositions of bodies.

35' The power of action of the Voltaic ap-
paratus, seems to depend upon causes similar
to those which produce the accumulation in the
Leyden battery namely, the property of non-
conductors and im perfect conductors to receive
electricar polarities from, and to communicate
them to conductors ; but its permanent action is
connected with the decomposition of the chemical
menstrua between the plates. Each plate of zinc
is made positive, and each plate of copper ne-
gative, by contact ; and all the plates are so ar-
ranged with respect to each other as to have their
electricities exalted by induction, so that every
single polar arrangement, heightens the electri-
city of every other polar arrangement ; and the
accumulation of power increases with the number
of the series. When the. battery is connected
in a circle, the effects are demonstrated by its
constant exhibition of chemical agencies, and
the powers exist as long as there is any men-
struum to decompose : but when it is insulated,
and the extreme poles of zinc and copper are

E 167 3

unconnected, no effects whatever are perceived
to take place, no chemical changes go on, and
it exhibits its influence only by communi-
cating very weak charges to the electrometer,
the end terminated by zinc communicating a
positive charge, that terminated by copper, a
negative charge.

That each plate of the most oxidable metal in
the apparatus, is in the relation of positive, and
each plate of the least oxidable, in the relation
ef negative, and that every series is possessed
of similar and equal polarity, is shewn by a very
simple experiment ; forty rods of zinc of the
same size, connected with forty silver wires
precisely similar, were introduced in the regu-
lar order into similar glasses filled with a solu-
tion of muriate of ammonia, rendered slightly
acid by muriatic acid ; as long as the extreme
parts remained unconnected, no gas was dis-
engaged from the silver, and the zinc was
scarcely acted upon; when they were connected,
all the plates of zinc were dissolved much more
rapidly, and hydrogene gas. was evolved from
every silver wire. And in another experiment,
in which several of these wires at equal dis-
tances were introduced into small glass tubes,
it was found that equal quantities of hydrogene
were produced,

36, It seems absolutely necessary for the ex-

[ 168 ]

hibition of the powers of the Voltaic apparatus,
that the fluid between the plates should be sus-
ceptible of chemical change, which appears to
be connected with the property of double po-
larity, of being rendered positive at one surface,
and negative at the other. There are substances
that are imperfect conductors, v/hich are capa-
ble of receiving only one kind of electricity,
when made parts of the Voltaic circuit, and
which M. Elirmans who discovered them, has
named unipolar bodies. Perfectly dry soap,
and the flame of phosphorus, when connected
with the two extremities of the Voltaic appa-
ratus, and with the ground, discharge only the
negative electricity. The flames of alcohol,
hydrogene, wax, and oil, discharge under like
circumstances only the positive electricity ; but
all these bodies when connected with one
pole only oF the pile, and with the ground,
destroy the divergence of the leaves of the
electrometer connected with that end. It is not
difficult to exhibit these phsenomena when the
atmosphere is dry, by means of two hundred
pair of plates carefully insulated : an insulated
gold leaf electrometer having a moveable wire
attached to it, should be connected with each end
of the pile : when either electrometer is brought
in contact with soap, the soap being connected
with Ihe ground, the slight divergence of the

[ 169 ]

leaves will cease; when the soap is connected
with both electrometers and with the ground,
the divergence of the leaves of the electrometer
connected with the end terminated by the zinc,
will continue, the leaves of the other electro-
meter will collapse. The opposite effect occurs,
when the flame of a taper is connected with
both electrometers and with the ground.

The unipolar conductors are incapable of
being active in any part of the pile, and in this
respect agree with nonconductors; many of
which, it is probable, if examined in their rela*
tions to electricities of low intensity, would
exhibit similar differences,

37- There are no fluids known, except such
as contain water, which are capable of being
made the medium of connection between the
metals, or metal of the Voltaic apparatus ; and
in cases in which Voltaic batteries have been
said to be constructed by metals and paper, or
metals and starch, or other like substances, the
feeble effects produced, are merely owing to
the small quantity of water adhering to these
substances, which will not act when carefully
dried. The instrument, called by M. de Luc,
the electrical column, formed of zinc, Dutch
leaf, and paper, and which he appears to con-
sider as a different combination from the pile of
Volta,, seems to be merely a feeble Voltaic appa^

[ 170 ]

ratus, in which the quantity of electricity is not
sufficiently great to produce any chemical chan-
ges, or distinct phaenomena of ignition ; but in
which the intensity of the small quantity exist-
ing, when the combination amounts to 40O or
500, is sufficient to enable it to affect the electro-
meter, and to act through a plate of air.

It is very probable that the power of water
to receive double polarities, and to evolve
oxygene and hydrogene, is necessary to the
constant operation of the connected apparatus ;
and that acids, or saline bodies, increase the
action, by affording elements which possess op-
posite electricities to each other, when mutually
excited ; the action of the chemical menstrua
exposes continually new surfaces of metal ; and
the electrical equilibrium may be conceived in
consequence, to be alternately destroyed and
restored, the changes taking place in impercep-
tible portions of time.

The manner in which aqueous fluids receive
and communicate electrical polarity, is sheww
by a very simple experiment ; let a number of
fine metallic surfaces or flattened wires (of tin
for instance) be made to swim in a narrow
trough containing water ; and let two wires from
the exiFeraities of a Voltaic battery of 1000
double plates, be plunged into- the remote ends
of the trough, one into one end, the other into

t 171 ]

the other end. The metals swiramhig on the
water will immediately acquire electrical po-
larity ; and the positive and negative poles will
be regularly opposed to each other, the pole of
the metal ©pposite to the wire positively elec-
trified, will be found to be negative, giving off
hydrogene, the other pole will deposite oxide ;
the next wire to this will present the alternate
order, which will be preserved in all of them ;
those most remote from the right line of the
circuit, will be least affected. If the battery
be in a , highly active state, tlie different
wires will attract each other by their opposite
poles, and Ihe circle will at length be closed
with the production of brilliant sparks. The
phasiiomena are precisely analogous to those
pbasnomena in magnetism, presented by a
number of flattened wires of soft iron, made to
swim upon water, and rendered magnetic by
the opposite poles of two powerful magnets ;
each wire has a north pole and a south pole;
and in the alternation, the different poles are
attractive of each other.

38. That the decomposition of the chemical
agents is connected with the enera^ies of the
pile, is evident from all the experiments that
have been made; as yet no sound objection has
been urged against the theory that the contact
of the metals destroys the electrical equilibrium,

[ 172 ]

and that the chemical changes restore ft ; and
in consequence that the action exists as long as
the decompositions continue ; and this conclu-
sion is confirmed by the late researches made
by M. M. Gay Lussac and Thenard, on the great
pile constructed by order of the French govern-
ment. The manner in which chemical changes
tend to restore the electrical equilibrium, is
shewn by a remarkable experiment on the elec-
trization of mercury, which I have very lately
made. A few globules of mercury are placed in
a vessel containing commsn pump water ; or any
water that contains a small quantity of saline im-
pregnation ; wires from a battery of iOOO double
plates, not very strongly charged, are introduced
into the vessel opposite to each other, so as to
reach the bottom ; as soon as the circle is com-
pleted, the mercury will be violently agitated,
each globule will become elongated towards
the positive pole, but will retain its circular
outline in the part opposite to the negative
pole ; oxide will be given off from this part,
which is positive, but no hydrogene from the
part which is negative, and the oxide will pass
in a rapid current from the positive towards the
negative pole. As long as no hydrogene is given
off, the globule is in contained agitation, and
a stream of oxide flows with great rapidity from
the positive to the negative surfaces ; and the

[ 173 ]

negative surfaces of the mercury approach
rapidly towards the positive, vkrhich are at rest ;
if the conducting power of the water is exalted
by the addition of more of the saline impreg-
nation, or if the charge of the battery be in-
creased, hydrogene will be given off from the
negative poles ; and the instant this happens
the globules become stationary ; as if the same
power which gave motion to the mercury was
neutralized by, or employed in, the evolution of
the hydrogene. There are many other remark-
able phsenomena connected with the operation
of electricity on mercury, in contact with water ;
which may be urged in favour of the idea, that
chemical and electrical attraction depend upon
the same cause, and which will possibly lead to
new views respecting the elements of matter ;
but the consideration of them properly belongs
to a more advanced division of this work.

39. The illustrious inventor of the new elec-
trical apparatus, has given it the name of the
electromotive apparatus, and has founded his
theory of its operation upon the Franklinian
idea of an electrical fluid, for which certain
bodies have stronger attractions than others;
and he conceives, that in his pile the upper
plate of zinc attracts electricity from the copper,
the copper from the water, the water again from

-E ]

the next plate of zinc, the next plate of zinc
from the next plate of copper, and so on.

This hypothesis applies very happily to
most of the phaenomena of the action of the
insulated pile, and the pile connected by either
of its extremities with the ground ; but does
not explain with the same facility, the powers
of the apparatus connected in a circle, in
which each plate of zinc must be supposed
to have the same quantity of electricity as each
plate of copper ; for it can only receive as much
as the copper can give, unless indeed the phse-
nomena of the circular apparatus be considered
as depending upon the constant and rapid cir-
culation of the natural quantity of electricity,
in the different series ; which requires the proof
of a constant power to attract electricity from
one body, at the same time that it is giving it
off, to another.

40. Whatever may be the happiest approxi-
mation to the true theory of the Voltaic instru-
ment, it can scarcely be doubted that the
electrical organs of certain animals depend
upon similar arrangements of exciting bodies.
The shock of the G/mnotus Electricus, and
the 7or/>^f/(3, resemble the Voltaic shock; and
the power resides in organs which consist of
^ number of similar alternations of different

[ 175 ]

substances. Tlie ejGTects are analogous to those
which a Voltaic apparatus of small surface, con-
sisting of very numerous but not very powerful
series, would produce. It has been conceived
that other phaenomena of living action may be
connected with the operation of weak electrical
powers; such a^ secretion ; and some ingenious
hints on this subject have been advanced by Dr.
Wjoliaston and Mr. Home, and some experi-
ments relating to the subject instituted by Mr.
Brande. Such enquiiies are worthy of further
pursuit, as they may tend to elucidate some im-
portant functions of the animal oeconomy : but
they must not be confounded with certain,
vague speculations, that have been advanced by
some authors, on the general dependence of
nervous or sensitive action, and muscular or
irritable action, upon electricity ; such specu-
lations are mere associations of words derived
from known phaenomcna, and applied illogi-
cally to unknown things. The laws of dead and
living nature appear to be perfectly distinct :
material powers are made subservient to the
purposes of life, and the elements of matter are
newly arranged in living organs ; but they are
merely the instruments of a superior principle.
As electrical changes are almost constantly
taking place in the atmosphere, and as the dif-
ferent substances composing the exterior of the

[ 176 ]

globe, bear different electrical relations to each
other, it is very probable that many of the che-
mical changes taking place on the surface, are in-
fluenced by the action of weak electrical powers :
such as the decomposition of the surfaces of
rocks, the modifications of soils, the formation
of acid, and developement of alkaline com-
pounds; and the mutual agencies of the ele-
ments in the earth, the sea, and the atmosphere,
may be assisted or modified by the circumstances
of general electrical action.

41. With regard to the great speculative
questions, whether the electrical phsenomena
depend upon one fl,uid, in excess in the bodies
positively electrified, and in deficiency in the
bodies negatively electrified, or upon two dif-
ferent fluids, capable by their combination
of producing heat and light, or whether they
may be particular exertions of the general at-
tractive powers of matter, it is perhaps impos-
sible to decide in the present imperfect state of
our knowledge. The application of electricity
as an instrument of chemical decomposition, and
the study of its effects, may be carried on inde-
pendent of any hypothetical ideas concerning
the origin of the pbaenomena; and these ideas
are dangerous only when they are confounded
with facts. Some modern writers have asserted
the existence of an electrical fluid with as much

[ "? ]

confidence as they would assert the existence
of water, and have even attempted to shew that
it is composed of several other elements ; hut
it is impossible in sound philosophy to adopt
such hasty generalizations; Franklin, Caven-
dish, Epinus, and Volta, the illustrious advo-
cates for the idea of a single electrical fluid, have
advanced it only as hypothetical, as accounting
in a happy way for most of the phaenomena ;
and none of the facts that have been brought
forward in favour of the actual existence either
of one or of two fluids, can be considered as
conclusive.

From a very ingenious experiment of Mr.
Cuthbertson, it appears that when a stream of
electrical sparks is passed through tlie flame of
a candle between two electrified surfaces, the
surface which is negative is most heated ; and
it has been argued that a current must pass from
the positive surface to the negative.

But it is more probable, that this phaenome-
non depends upon the positive unipolar qualiij-
of the flame of wax or tallow referred to above ;
for supposing this flame to become positive,
which would seem to be the case, it must be
attracted by the negative, and not by the posi-
tive surface and this view is confirmed by an
experiment I made on an arch of flame between
the two poles of the great Voltaic apparatus of

VOL. I, N

[ 178 ]

2000 plates. Platina melted with more fa-
cility in the arch at the positive than at the ne-
gative extremity, and this arch was common air
intensely ignited, through which the electricity
was discharged ; and if any mechanical current
existed from the positive pole to the negative,
the maximum of heat must have been produced
at the negative. When a wire of platina
was made positive, and brought in contact with
charcoal rendered negative, it became ignited
much sooner, and fused into larger globules,
than when made negative, and brought in con-
tact with the charcoal rendered positive ; and
that the effect did not depend upon the greater
heat of the charcoal, appears from the circum-
stance, that similar phsenomena occurred when
the experiment was made by contact with mer-
cury. But when an imperfectly conducting fluid,
such as sulphuric acid, was used, the result was
reversed. The wire being negatively electrified,
and the acid positively, the point in contact
with the surface of the acid instantly became
white hot ; in the opposite case a spark of blue
light only was produced.

The different appearance of the light on
points positively and negatively electrified, has
been urged in favour of the idea of a fluid pro^
ceeding from the positive to the negative sur-
face. This phsenomenon occurs as well in the

179 ]

Voltaic, as in the common discharge: for when
the arch of flame passes between two points
of charcoal, a vivid spot of white light is al-
ways perceived on the negative point, and rays
seem to diverge from the positive point. The
effect of the dijBPerence of the appearance of diffe-
rently electrified points, I find, does not depend
upon the nature of the elastic medium, for it takes
place in hydrogene, carbonic acid, and chlorine,
though it is less distinct in the heavier gasses,
probably from their being worse conductors ; but
the affections of light in passing from the dif-
ferent parts of the circuit, can with no more
propriety be urged in favour of a specific fluid,
than the chemical changes produced by the
different poles.

When folds of paper are perforated by a
discharge from an electrical jar, there is a burr
on both sides, which may be urged as an argu-
ment against any fluid passing through ; for it
could penetrate in one direction only, and the
experiment is favourable to the idea that elec-
tricity is an exhibition of attractive powers
acting in peculiar combinations, for the sub-
stance of the paper which was negative, may
be conceived violently attracted to the positive
surface, and the part which was positive, to the
negative, at the moment the discharge tak^s
place*

It will be useless to pursue any further tbi»

N 2

[ 180 ]

recondite part of the subject; whatever view is
taken, active powers must be supposed to be
bestowed upon some species of matter, and the
impulse must be ultimately derived from the
same source. In the universe, nothing can be
said to be automatic, as nothino; can be said to
be without design. An imperfect parallel may
be found in human inventions ; springs may
move springs, and wheels, indexes ; but the
motion and the regulation must be derived from
the artist; sounds may be produced by undu-
lations in the air, undulations of the air by
vibrations of.musical strings ; but the impulse
and the melody must arise from tlie master.

VIII. On Anal/sis and Synthesis ; on the Circiim-
stances to be attended to in these Operations, and
on the Arrangement of undecompoimded Bodies.

I. When a substance is capable of being
resolved into other forms of matter, it is said
to be compounded; thus, if mild magnesia,
(subcarbonate of magnesia) be strongly heated
for an hour in a green glass retort, having its
beak connected with a flaccid bladder, elastic
matter will collect in the bladder; and the
magnesia, when examined, will be found to
have lost in weight, and to be altered in its
properties, it will not effervesce with acids, and
It is harsher to the feel. The weiffht oi the
elastic matter collected in the bladder is exactly

[ 181 ]

equal to that lost by the magnesia ; it cannot by
any means be converted into magnesia, and the
mild magnesia gives only a limited quantity oF
it ; so it is evident that mild magnesia consists
of a matter which can be rendered permanently
gaseous, and a fixed substance; it is a com-
pounded body.

The metal called zinc, if heated strongly in
close vessels, rises in the elastic form, but when
condensed by cold, it appears unaltered in its
properties. It may be distilled any number of
times, but it wiii be still the same : nothing
permanently elastic will be given off from it ;
and if the operations be conducted with care,
it will be found undiminished in weight. Not
even the intense heat of the Voltaic battery ap-
plied in a vessel exhausted of air, effects any
change in it; it easily enters into new combi-
nations, but can be resolved into no other
forms of matter; it is considered as an undecom»
pounded body.

The term element is used as synonymous with
undecompounded body ; but in modern chemistry
its application is limited to the results of ex-
periments* The improvements taking place in
the methods of examining bodies, are constantly
changing the opinions of chemists with respect
to their nature, and there is no reason to sup-
pose that any real indeslructibk principle haes

I m ]

been yet discovered. Matter may ultimately be
found to be the same in essence, differing only
in the arrangements of its particles ; or two or
three simple substances may produce all the va-
rieties of compound bodies. The results of
our operations must be considered as offering
at best approximations only to the true know-
ledge of things, and should never be exalted as
a standard to estimate the resources of nature.

2. By analysis compounded bodies are re-
solved into their constituents ; hy sj^nthesis they
are produced in consequence of the union of
these constituents ; and when the weight of the
compound corresponds to that of the constitu-
ents, the processes are considered as accurate.

The words analysis and synthesis are applied
incases when bodies are resolved into, or com- -
pounded from, any other forms of matter, with-
out relation to the elementary nature of these
forms ; — thus crystals of Glauber's salt may
be resolved analytically into sulphate of soda
and water, or compounded synthetically from
these substances ; and sulphate of soda may be
formed by synthesis from sulphuric acid and
soda, both of which are compounded bodies-

3. In all conclusions upon the results of
analytical and synthetical experiments, it is of
the greatest importance that the agencies of all
the substances concerned, should be accurately

[ 1^3 ]

known, that no circumstance should be taken
for granted, and that the nature of the real
constituents of the body should be shewn to be
unchanged during the process.

Whatever instruments of experiments be
used, their relations to the substances acted
upon should be well known, and their influ-
ence fif any) estimated. Thus if a hard stone
be pulverized in a mortar of porcelain, agate,
or iron, the comparison of weights before and
after the process, should be carefully made, to
ascertain what quantity of matter may have
been abraded from the mortar. When sub-
stances are fused, or heated, in vessels on which
they are capable of acting, the same precautions
should be taken. It should either be shewn,
that the vessel has been unchaneed durins; the
operation, or the nature and extent of the
change should be demonstrated.

Many celebrated chemists have been led into
error in the infancy of their investigations,
from a want of attention to these circumstances.
Thus the illustrious Scheele for some time sup-
posed that silicious earth was composed of
fluoric acid and water, because he obtained it
by mixing together an acid gas, (procured from
fluor spar) and water ; but subsequent experi-
ments, by demonstrating the loss of weight of
the glass vessels in which his operations were

[ 184 ]

conducted, shewed that the silicious earth was
derived from these vessels, and dissolved in the
gas.

4. Water is tlie great solvent employed in
chemical processes, and its operation therefore
should be strictly attended to. It has been too
much the custom to consider its elements as
almost passive in the processes of dissolution
and decomposition ; but there are a number of
instances in which these elements are newly
arranged, and in which their transfer and
changes produce very important phenomena.

When oxymuriatic or chlorine gas is ex-
posed to light, it undergoes no change, but
when a solution of it in water is placed under
the same circumstances, oxygene gas is given
off, and a solution of muriatic acid is found in
the water. Hence it was concluded, without
any reference to v/eights, that oxymuriatic gas
consists of muriatic acid gas and oxygene, and
that the water acted in no other way than in
assisting the expulsion of the oxygene, by its
attraction for the muriatic acid gas.

This inference, however, is now known to be
incorrect, and it affords a striking instance of the
present object of discussion. If aqueous vapour
in small quantities, and chlorine gas, be passed
through an ignited tube of glass, the steam en-
tirely disappears, and oxygene gas, and muriatic

[ 185 ]

acid gas are formed ; therefore the water must
have entered into the composition of the mu-
riatic acid gas, or must have been decomposed ;
its hydrogene combined with the chlorine, to
form muriatic acid gas, and the oxygene gas
set free ; and that hydrogene actually enters
into the composition of muriatic acid gas, is
proved by the experiment detailed in page 111;
nor can oxygene gas be procured in any expe-
riments upon chlorine, in which bodies not
known to contain oxygene, alone are concerned ;
nor have any means been found by which this
substance can be decompounded.

To give another example: when concentrated
oil of vitriol, which consists of sulphuric acid
and water, is poured upon common salt, and
they are heated together, muriatic acid gas flies
off, and sulphate of soda is obtained ; hence it
was concluded, that common salt consists of
muriatic acid gas and soda : and that the sul-
phuric acid merely displaced the muriatic acid
gas ; and no account was taken of the water of
the sulphuric acid in the operation; yet the
whole change depends upon this water: and
no soda and no muriatic acid can be procured
from common salt, without water ; and common
salt is made directly by heating sodium, th^
metal which I discovered to be the basis of soda,
and chlorine together, and th^se are both as yet

[ 186 ]

undecompounded bodies ; and if 92 parts of oil
of vitriol, which consists of 75 parts, by weight,
of sulphuric acid, and 17 parts of water, be
made to act upon 111 parts of common salt,
which consists of 44 sodium, and 67 chlorin^^
the water will be decomposed, 15 of oxygene
will combine with the sodium to form 59 of
soda, and 2 of hydrogene will combine with
67 of chlorine to form 69 of muriatic acid gas,
and the sulphate of soda will be I34 parts.

5. There are numbers of substances which
possess an attraction of a peculiar kind for
water; they absorb water without undergoing
any remarkable change in their properties, and
in small proportions. Such are charcoal, dif-
ferent earths, and animal and vegetable sub-
stances. If well burnt charcoal be exposed to
the atmosphere for some days, it will increase in
weight from 10 to I4 grains per cent., and the
increase is almost entirely owing to its absorbing
water, which existed in the form of vapour in
the air ; and by heating charcoal that has been
exposed to air, in close vessels, the water may be
collected unaltered. Baryta, strontia, and lime,
absorb definite proportions of water, and form
what are called hydrates, in which the water
18 in chemical combination, and requires an
intense heat for its expulsion ; and magnesia,
alumina, silica, glucina, and zircona, likewise

[ 187 ]

increase in weight by attracting aqueous vapour
from the atmosphere, and seem to form analo-
gous combinations ; they give off all the water
they had absorbed at the temperature of dull
ignition, so that it is retained in them by a very
weak attraction ; and that the water absorbed
in this way, is in true chemical union with the
earths, is still farther proved by the circum-
stance that a hydrate of one of these bodies,
exists in nature, namely, the wavellite or hy-
drate of alumine, and this is a crystallized body,
and requires a strong red heat for the expulsion
^o£ its water.

Compounds of the earths in fine powder,
that have been heated red, increase in weight,
from the absorption of atmospheric moisture :
and the case is the same with almost all sub-
stances, except the metals, and certain inflam-
mable bodies ; so that in all experiments of
analysis, the solid products obtained, should
be strongly heated, and weighed whilst warm,
and before they have been long exposed to
the atmosphere, or the quantity of water they
have absorbed should be exactly known. And
the same precautions should be used, and more
strictly, with respect to alkaline, acid, and
saline bodies that enter into chemical combi-
nation with water, and attract it rapidly from
the atmosphere.

[ 188 ]

6. Gaseous bodies are usually procured from
substances that contain water, and many of
them are collected over water ; it is therefore
of considerable importance in analytical pro-
cesses, that their relations to this substance
should be distinctly understood.

It has been already stated, that common air
contains aqueous vapour, or water in an invi-
sible elastic form, which is greater in propor-
tion as the temperature is high, air at the tem-
perature of 65° Fahrenheit, containing about
-jV of its volume. From the experiments of
Desormes and Clement, it appears that all the
gasses not absorbable to any extent by water,
such as oxygene, azote, carbonic acid, and
hydrogene gasses, contain in equal volumes,
the same quantity of vapour as common air ; so
that vapour, when it exists in these bodies, can
only be regarded as mixed with them ; and it
is separated by substances that have a strong
chemical attraction for water, such as lime, mu-
riate of lime, sulphuric acid, hydrate of potassa,
8cc. ; and in all accurate experiments in which
gasses are examined, they should be previously
freed from vapour by exposure for some hours
to substances that have a strong attraction for
water, but possessed of no chemical action on
the gas.

The relations of water to gasses with which

[ 189 1

it is capable of combining chemically, (which
gasses will be described hereafter,) are very
different. It is evident that no pure aqueous
vapour can exist in them in a state mixture ^
but they may, and probably in almost all cases
do contain a gaseous compound of water, and
the peculiar elastic fluid. If a drop of water
be introduced into a flask filled with amrlio-
niacal gas, it rapidly absorbs the gas, and in-
creases in size ; but if a minute drop of a con-
centrated solution of ammonia be introduced,
and the temperature of the flask be gently
raised, the drop disappears, and continues in-
visible, as long as the heat is preserved uniform.
The instances are similar when analogous ex-
periments are made upon muriatic acid and
silicated fluoric acid gasses ; and I have found
that these elastic fluids collected at the tempera-
ture of 75° deposited a slight dew, consisting of
strong solution of acid in water, when intensely
cooled by a freezing mixture. There is reason
to believe that the case must be the same with
fluoboric acid, and that this body may contain
a minute quantity of the compound which may
be called hydrate of fluoboric acid ; and this is
confirmed by the phenomena of the action of
potassium upon the gas, for 1 have never been
able to decompose it by this substance, without
procuring small quantities of hydrogene.

[ 190 ]

The quantity of water in the gasses for
which it has a chemical attraction, must depend
upon the degree of volatility of the fluid com-
pound of the gas and water, and upon the
proportion of water it contains. Sulphureous
acid gas, which has only a Weak attraction
for water, would, there is every reason to
believe, contain most of the gaseous hydrate ;
but even in this it is most likely there
must be less water than in common air at the
same temperature ; ammonia would probably
be next in order, then silicated fluoric gas, mu-
riatic acid gas, nitrous acid gas, and, last of all,
fluoboric gas.

The temperatures at which the compounds
of water and gasses rise in vapour, seem to de-
pend upon the strength of the attraction, by
which they are combined, and upon the degree
of volatility of the gaseous element. All solu-
tions of sulphureous acid, and ammonia, boil at
temperatures which differ very little from the
boiling point of water. The highest point of
the ebullition of solution of muriatic acid gas in
water is about 232° Fahrenheit ; that solution
of nitric acid which gives a compound vapour,
does not boil at a temperature below 248° ; the
temperature at which hydrated fluoric acid boiis^
according to M M. Gay Lussac and Thenard,
is not very high ; but the vapour contains a

[ 191 ]

considerable quantity of water, compared with
other acid vapours.

Whether substances will attract water from
the absorbable gasses, must depend upon the
strength of their affinity for water, as compared
with that of the gas. Dry hydrate of potassa
will slowly attract moisture from ammonia, and
dry muriate of lime from sulphureous acid gas ;
but muriate of lime does not appear to act upon
the water in muriatic acid gas, Silicated fluoric
acid gas and fluoboric gas, instantly render
cloudy sulphureous acid gas by attracting
moisture from it, and fluoboric gas, if mixed
with fluoric acid gas, renders it very slightly
cloudy. Probably there are no substances
which will attract water from the vapour of
hydrated fluoboric acid ; but the quantity is
too minute to influence to any extent, the results
of experiments on gasses containing it.

In cases when elastic fluids are produced in
contact with substances which afford peculiar
vapours, such as volatile oils, alcohol, ether,
See. ; these vapours should be separated either
by agitating the gasses in water, or solutions
of substances which are capable of absorbing
them, such as solution of potassa, 8cc. and the
aqueous vapour separated afterwards by the
means above mentioned.

[ 192 ]

7. In stating the weights, of bodies which
are the results of analytical experiments, the
temperature should be noticed ; and in the
case of elastic fluids, the degree of pressure of
the atmosphere, as indicated by the barometer.
When gaseous compounds are resolved into
simpler gaseous bodies, or when gasses are com-
pared with each other, as they are all similarly
affected by heat and pressure, there is no ne-
cessity for any specific statements of these cir-
cumstances, and in describing the specific gra-
vity of a gaseous body, it is necessary only to
give the relation of its weight to that of air;
thus the v/eight of air being 1000, that of
oxygene gas will be 1097. As hydrogene gas
is much lighter than any other elastic fluid,
and as it is the body which combines with
other substances in the smallest proportions, it
would perhaps assist the progress of chemical
inquiry to denote its specific gravity, by unity,
which would harmonize with the idea of repre-
senting the proportion in which it combines
likewise by unity, and would facilitate the
means of comparing the absolute weights of
gaseous bodies concerned in experiments, with
the numerical symbols representing their ele-
ments. The specific gravity of hydrogene
being considered as 1, that of common air will

C 193 ]

be 13-7, and that of oxygene, as has beeii
stated in page 1 12, 15.

8. In treating of the different substances
which, by their agencies, combinations, or de-
compositions, produce the phgenomena of che-
mistry— radiant ox ethereal matters , will be first
considered, as their principal effects seem ra-
ther to depend upon their communicating
motion to the particles of common matter, or
modifying their attractions, than to their ac-
tually entering into combination with them ;
and as from the laws of their motions, or from
their extreme subtileness, they are incapable of
being weighed.

The undecompounded substances which are
permanent in their forms, will be considered in
an order of arrangement depending upon their
electrical relations ; those determined to the
positive surface in the Voltaic electrical circiait,
being arranged in one class, and those determined
to the negative surface in another; and the sub-
divisions of the classes will be made according
to their natural relations.

The general principle adopted will be, that
no compounded body shall be treated of, tiUits
constituents have been described.

The relations of bodies derived from their
electrical powers, are coincident with those de-
pendent upon their agencies in combustion;

VOL. I. O

[ 194 ]

that Is, one class contains supporters of combus-
tion, and the other class combustible bodies ;
but as the heat and light produced in combus-
tion, seem to be merely indications of the
strength of attraction of the acting substances ;
and as these phaenomena occur in cases in which
inflammable matters act upon each other, com-
bustibility can scarcely be considered as a defi-
nite idea ; though the importance of the common
phaenomena of combustion, have made them
the grand objects in all the early theories of
chemistry.

r 195 ]

DIVISION II.

OF RADIANT OR ETHEREAL MATTER.

i. Of the Effects of radiant Matter, in •producing
the Phenomena of Vision.

1. The phasnomerp of vision depend upon
the presence of the sun, of the heavenly bodies,
or on the mutual action of certain substances on
the surface of the earth.

2. It has been demonstrated by Roemer, and
confirmed by the discoveries of Bradley, that the
motion of light is progressive ; it is about eight
minutes in passing from the sun to the earth.

$. When light is entirely intercepted by
a body placed between the luminous object
and the^ye, that body is said to be opaque;
and the manner in which the light is inter-
cepted, proves that it proceeds in right lines or
rays from the luminous body as a center.

4. Luminous objects may be seen through
certain substances ; and these bodies are said to
-be transparent. Bodies differ considerably in
the degree of their transparency ; some trans-
mit many more rays than others, and there are
gradations from perfect opacity, when all the

0 2

[ 196 ]

rays are intercepted, to a high degree of trans-
parency, when by far the greater number are
transmitted.

5=^ Of the rays that are not transmitted, some
are lost, as it were absorbed by the body ;
others are thrown back again, or reflected from
its exterior or inner surfaces, and these rays are
called reflected rays.

6. The rays of light in their transmission
through bodies, or reflection from their sur-
faces, undergo certain modifications, of great
importance in their connection with the laws
of vision, and the general properties of radiant
matter.

7» If rays of light pass from one transparent
substance not crystallized into another, in an
oblique direction, their path is altered, and they
are bent downwards or upwards, according as
the medium is more or less dense, or according:
as it differs in chemical qualities ; inflammable
substances, or compounds containing inflam-
mable substances, having the highest power of
bending towards the perpendicular or of refract-
ing, as it is called, the rays of light ; and, in
th e same substances, the sines of the angles of re-
fraction bear always the same relations to those
of the angles of incidence.

8» The rays of light in.passing through obli-
quangular crystalline bodies, follow different

[ 197 3

laws. If a ray of light be received perpendicu-
larly upon a plain surface of island crystal, or
rhomboidal carbonateof lime, onepartof itpasses
through without altering its direction ; another
part, on the contrary, is refracted in a plane
parallel to the diagonal, joining the two obtuse
angles of the crystal, so that images seen through
the crystal appear double ; and this phseno-
menon, first scientifically reasoned upon by
Huygens, is called the phsenomenon of double
refraction.

If a ray of light which has suffered double
refraction from one crystal, be received by
another crystal placed in a similar and parallel
position, there will be no new division of rays,
and no change in their direction ; but if the
second crystal be placed, so that its planes of
perpendicular refraction are at right angles to
those of the first crystal, then there will be a new
phsenomenon, and that part of the ray which be-
fore passed through the ordinary refraction, will
receive the extraordinary refraction, and recipro-
cally that which underwent the ordinary will suf-
fer the extraordinary refraction. If the second
crystal be turned gradually round in the same
plane, when it has made a quarter of a revolution^
there will be four divisions of the ray, and they
will be reduced to two in the half of the revolu-
tion, so that the retracting power depends upoD

[ 198 ]

the relations of the position of the particles of
the crystals, to the rays passing through them.

Similar phsenomena to those presented by
island crystal, are exhibited in a greater or
less degree by other crystalline bodies, and pro-
bably would belong to all of them, if they were
siiEciently transparent to admit of the passage
of light through strata of considerable thick-
ness. Very thin pieces of the rhomboidal car-
bonate of lime even do not give perceptibley
double images.

9. When light is reflected from bodies ;
under most circumstances it is unaltered in its re-
lations to the refractive powers of transparent
substances, and the angle of reflection is equal
. to the angle of incidence. But, in certain cases,
at angles which differ for diflPerent bodies, the
reflected rays have the same property as the
extraordinary refracted rays, that have passed
through island crystal. This important fact,
discovered by M. Malus, is easily exemplified.
If the flame of a taper reflected at an angle of
5£° 45' from the surface of water, be viewed
through a piece of double refracting spar, one
of the images will vanish every time that the
crystal makes a quarter of a revolution.

If a ray of light be reflected from a surface of
glass, at an angle of 54.35', and fall upon ano-
ther plane of glass at the same angle, it will

[ 199 ]

suffer no new reflection, and will pass through
the glass unaltered, provided that the planes of
reflection or refraction be perpendicular to each
other; but if they are in the same direction,
nothing i"emarkable will happen.

Direct light is most copiously reflected, as its
incidence is less perpendicular ; but light once
reflected follows different laws, and the quantity
that suffers the second reflection, depends en-
tirely upon the relations of the angles made by
the reflecting surfaces with the rays.

10. When a ray of light is made to pass
through a triangular prism of glass, and the
transmitted light is received upon a sheet of
white paper, it is found to be of different colours;
the most distinct of which are red, orange, yel-
low, green, blue, indigo, and violet. Newton
has ascertained, that if the coloured image, or
spectrum, as it is called, be divided into 360
parts, the red will occupy 45 of these parts, the
orange 27, the yellow 48, the green 60, the
blue 60, the indigo 40, and the violet 80. The
red rays are least refracted, the violet rays
most, and the other coloured rays are refran-
gible inversely, in the order in which they have
been named.

According to Dr. Wollaston, when the beam
of light is only ~ of an inch broad, and received
by the eye at the distance of ten feet, through a

[ 200 ]

clear prism of flint glass, four colours only ap-
pear, red, yellowish green, blue, and violet.

If the differently coloured rays of light separ-
ated by the prism, be concentrated upon one
spot by means of lenses, they produce white
light ; and Newton has beautifully explained
the different colours of bodies, by supposing
that they retain certain of the coloured rays of
light, and reflect others ; thus red bodies are
supposed to reflect red light, and to absorb all
the other coloured rays.

The different coloured rays of light, as has
been shewn by Dr. Herschel, differ in their
power of rendering objects visible ; at least in
the state of division, which is obtained by means
of a prism. If an equal portion of these rays be
made to illuminate a printed page, the words
may . be seen from the greatest distance, when
exposed to the lightest green or deepest yellow
light ; and the effects of illumination for equal
quantities of the rays, diminish from the cen-
tral parts towards the extremities of the spec-
trum. It may, however, be said that there are
more green rays in a given part of the spectrum
than blue raySj and the difference of illuminating
power may depend on this circumstance.

11. The rays separated by one prism are not
capable of being further divided by being passed
through another; and in their relations to

f

[201]

double refraction and reflection, they appear to
agree with direct light: an object illuminated
by any of the rays in the spectrum, is seen
double through island crystal, in the same
manner as if it had been visible by white
light.

12. The minute investigation of the proper-
ties of radianf matter, in their relations to the
phaenoroena of visiorij constitutes the object of
a particular branch of science — Optics. The few
statements that have been made on this subject,
it will be found in the following pages, are con-
nected with the chemical effects and nature of
radiant matter ; and it will immediately be seen,
that the same causes which produce the most,
numerous and important of our sensations, and
which give, as it were, language to the ex-
ternal world, are likewise subservient to the
orderly successioii of events in the oeconomy of
nature.

XL Of the Operation of radiant Matter in produc-
ing Heat.

1. When similar thermometers are placed in
the difierent parts of the solar beam, separated
by the prism, it is found that different effects
are produced in the different coloured rays.
The greatest heat is exhibited in the red rays,

[ ,202 ]

the least in the violet rays ; and in a space
beyond the red rays, where there is no visible
light, the increase of temperature is greatest of
all. This important discovery was made by
Dr. Herschel* He estimates the power of
heating in the red rays, to be to that of the
green rays as 55 to 26, and to that of the violet
rays as 55 to 16. A thermometer, in the full
red rays, indicated an increase of temperature
of 7° Fahrenheit in ten minutes ; beyond the red
rays, in an equal time, the increase was 9° Fah-
renheit.

2. From these facts, which have been con-
firmed by Sir H. Englefield, and other good
observers, it is evident that matter set in motion
by the sun, has the power of producing heat
without light, and that its rays are less refran-
gible than the visible rays.

Some persons have concluded from the phse-
nomena, that all the rays which produce heat
in the solar beam, are distinct from those that
produce light; but this does not seem to be
warranted by the experiments, for if it were tlie
case, they would, probably, be entirely separated
from the coloured rays by the prism, as the
coloured rays are from each otiier. It has
been used as an argument, in favour of the dis-

* Philosophical Transactions, 1800, p. 26 1.

[ 203 ]

tinctness of the rays producing light, and those
producing heat, that the beams from the moon
illuminate without heating ; but it is possible
that a greater number of the most heat making
rays, than of the other rays, may be absorbed
by that planet ; and supposing all the rays re-
flected that fail upon the moon, yet still their
intensity would be 9589O times less than that of
the solar rays, at the surface of the earth ; and
it appears from experiment, that the real inten-
sity of the ligh t of the moon to that of the sun
is less than 1 to 300,000, and such rays con-
centrated by the most powerful lenses, could
not be expected to produce any effect on com-
mon thermometers ; and as yet no very deli-
cate experiments have been published on the
subject.

3, The invisible rays that produce heat, are
capable of reflection as well as refraction, in the
same manner as the visible rays. It is well
known that an intense degree of heat may be
produced by the concentration of the solar
beams upon a single spot, by a concave mirror,
or by several mirrors ; and there is no reason
to disbelieve the possibility of the inventions
ascribed to Archimedes, who, it is said, by the
combined effect of a number of plane mirrors,
set fire to the Roman ships during the siege of
Svracuse ; thoup^h the immense means and labour

[ 504 ]

required for such an operation, renders the
narrative very doubtful.

4. Rays capable of producing heat with and
without light proceed from bodies at the sur-
face of the globe under peculiar agencies or
changes, as well as from the sun ; and the phze-
nomena that are usually called the phscnomena
of the radiation of terrestrial heat are of great
extent and importance, and well worthy of be-
ing studied.

5. If a thermometer be held near an icrnited
body it receives an impression connected with
an elevation of temperature: this is partly pro-
duced by the conducting powers of the air;
but it is likewise partly produced by another
impulse which is instantaneously communicated,
even to a considerable distance. If a laro-e con-
cave metallic mirror be placed upon the ground,
and the hot body be raised some feet above it,
a thermometer will instantly rise in the focus of
the mirrorj though it is evident that no current
of hot air can pass downwards from the body.

This effect is commonly caUed the radiation
of terrestrial heat. It is best observed, by em-
ploying two mirrors parallel to each other, and
to the surface of the earth. If the mirrors be
of copper tinned, and be well polished, and as
much as 2 feet in diameter, and distant ordy
12 feet, a small pan of red hot charcoal, placed

[ 505 ]

in the focus * of the upper mirror, will cause
gunpowder to explode in the focus of the lower
mirror.

6. In cases when no light is emitted from a
hot body, the effect of the concentration of
heat by the mirrors may still be produced.
Thus, if a vessel filled with boiling water, be
placed in the focus of the upper mirror, a ther-
mometer placed in the focus of the lower one
will have its temperature increased.

These phaenomena of the radiation of terres-
trial matter producing heat, were made known by
the academicians Del Cimento, Hooke, Scheele,
and Pictet : and there is another fact, still more
extraordinary, which has been called the radicif
Hon of cold, first observed by the Italian philso-
phers, and afterwards by Pictet. If in the ar-
rangement of the two parallel mirrors, a piece
of ice be introduced into the lower focus, the
thermometer in the upper focus will indicate a
diminution of temperature.

7. All these phaenomena coincide with the
phaenomena of the reflection of the solar beams ;
and even the apparent radiation of cold is in har-
mony with them ; for if it be supposed, that rays

• In the usual form of the experiment, the mirrors are
placed opposite to each other on the ground. This arrange-
ment, which I have been long in the habit of employing, in
the demonstrations in the Theatre of the Royal Institution,
more distinctly exhibits the effect. See Plate IV. Fig. 21. j

1

I 206 ]

capable of producing heat, emanate from all ter-
restrial bodies, but in quantities greater in some
increasing proportion as their temperatures are
higher, then the introduction of a cold body into
the focus of one mirror, ought to diminish the
temperature of a thermometer in the focus ofthe
other, in the same manner as a black body-
placed in one focus, would diminish the quantity
of light in the other focus ; and the eye is to the
rays producing light, a measure, similar to that
which the thermometer is to rays producing heat.

8. If a large lens be placed before an ignited
body, and the I '^ht be refracted to a focus, a ther-
mometer placed in the focus will be very slowly
affected. The increase of temperature will be in-
finitely less than that produced in the focus of a
mirror of the same size, and is such as may be
principally ascribed to the increased radiation of
heat by the lens itself. Likewise, if glass screens
be placed between the two mirrors, in the experi-
ments in which the ignited coals, or water, or ice
are used, the effect is in great measure destroyed.
This establishes a difference between the agency
of the radiant matter producing heat on the
surface of the earth, and of that from the sun.
Mr. Leslie has supposed that the phsenomena
ofthe radiation of terrestrial heat, depend upon
certain pulsations or undulations of the atmos-
phere capable of being reflected, but not of

[ 207 J

being refracted ; but none of his facts prove this
ingenious hypothesis, though many of them are
favourable to it, I had an apparatus made, by
which platina wire could be heated in any elastic
medium, or in vacuo ; and by which the effects
of radiation could be distinctly exhibited by
two mirrors, the heat being excited by a Voltaic
battery. In several experiments, in which the
same powers were employed to produce the
ignition, it was found that the temperature of a
thermometer rose nearly three times as much
in the focus of radiation, when the air in the re-
ceiver was exhausted to ~— , as when it was

I20'

in its natural state of condensation.* The
cooling power, by contact of the rarified air,
was much less than that of the air in its
common state, for the glow of the platina was
more intense in the first case than in the last ;
and, this circumstance perhaps renders the ex-
periment not altogether decisive, but the results
seem favourable to the Idea, that the terrestrial
radiation of heat is not dependent upon any
motions or affections of the atmosphere.

9. Another fact coinciding with this opinion,
is found in the effects of the refraction of the
rays from charcoal, ignited by Voltaic electri-
city. When a small lens was placed before the
brilliant star of light, produced by the battery

* See Plate IV. Fig, 22.

[ 208 j

of two thousand double plates, and its focus
thrown upon the ball of a small differential
thermometer, the instrument instantly indicated
an elevation of temperature.

10. The manner in which the temperatures
of bodies are affected by rays producing heat,
is different for different substances, and is very
much connected with their colours. The bodies
that absorb, as it is called, most light, and of
course that reflect least, are most heated when
exposed either to solar or terrestrial rays. Black
bodies in general are more heated than red ;
red more than green ; green more than yellow ;
and yellow more than white.

Metals are less heated than earthy or stony
bodies, or than animal or vegetable matters.
Polished surfaces are less heated than rough
surfaces.

11. The bodies that have their temperatures
most easily raised by the action oi' rays produc-
ing heat are likewise those that are most easily
cooled by their own radiation, or that at the
same temperature emit most heat making rays.
Metals radiate less heat than glass j glass less
than vegetable substances ; and charcoal has the
highest radiating powers of any body as yet
made the subject of experiment

From Mr. Leslie's ingenious researches, it
appears that the radiating power of lamp-black,

[ 209 ]

being; taken as 100 : the fbllowina; substances
radiate in a proportion that mav be thus ex-
pressed. Sealing wax, 95 : crown glass 90 ;
China ink S8 ; ice 85 ; minium 80; isinglass
80; plumbago 75; tarnished lead 45; clean
lead 19; polished iron 15; tin plate, gold,
silver, and copper 12.

IQ. There are some practical applications of
the doctrines of radiant Iseat, to the (Economy
of some of the useful arts and processes of com-
mon life.

Vessels that are intended to retain their heat,
should be metallic and highly polished ; and,
independent of elegance and delicacy, there is
a reason obvious, from the preceding facts, why
metallic vessels for the purposes of the table,
should be kept as bright as possible. Steam or
air pipes for warming houses, should be polished
in those parts where the heat is not required to
be communicated, and covered with some ra-
diating substance, such as lamp black, or plum-
bago, in those rooms v/hich arr to be heated by
them.

Culinary implements should be blackened,
and not polished on those parts, which are
to receive heat. The heated surfaces of fire-
places or stoves should not be metallic ; but of
stony or earthy materials, and in this case much
more heat will be communicated by radiation.'*

* Count Rumford. Phil. Trans. ]804i page IfS,
VOL. I. P

[ .910 ]

HI. Of the Effects of radiant Matter in producing
chemical Changes.

1. A number oFthe effects of radiant matter in
producing chemical changes, may be ascribed to
its poAvers of heating bodies. The heat produced
by the concentration of rays has been ah'eady
referred to, and the focus of a powerful lens or
mirror exposed to the sun, offers means of ex-
cidng heat inferior only to those afforded by
Voltaic electricity. In some cases the direct
solar light produces effects similar to those pro-
duced by a degree of heat much higher than
could be excited by their influence upon an
opaque body, thus as M. Gay Lussac, Thenard,
and Dalton have shewn, chlorine and hydros;ene
detonate when a mixture of them is exposed to
the solar beams, though the same effect is nol
produced by the application of a heat below
that of ignition. This has been explained by
supposing that the temperature of particles of
substances is raised considerably and instanta-
neously by the rays ; but it may likewise, and
with more probability, be supposed to depend
upon a specific and peculiar influence of radiant
matter, and that such an influence exists, is
proved by many circumstances.

2. If moist horn silver, muriate of silver
I' N, be exposed to the different rays in the

[211]

jprlsmatlc spectrlim ; it will be found that
no effect is produced upon it in the least re-
frangible rays, which occasion heat without
light, a slight discqloration only, will be occa*
sioned by the red rays, the effect of blackening
will be e-reater towards the violet part of the
spectruiii, and in a space beyond the violet,
where there is no sensible heat Or li^ht, the
ehemical effect '*v!i] be very distinct.

This observation made by M. Ritter, and
Dr. Woliaston, proves, that there are rays more
refrangible than the rays producing light and
heat; and from the observations ofM. Berthol«
let, it appears, that muriatic acid gas is formed
v/hen horn silver is blackened by light, so that
they may be called hydrogenating rays.

S. It has been supposed that these invisible
rays are mixed with the other rays throus;hout
the coloured part of the spectrum ; but it seems
equally probable, that the same rays that pro-
duce light, may likewise produce chemical
effcctSj and effects of heat ; and Dr. Young has
shewn that the invisible fays are liable to the
same affections as visible rays, when they are
reflected from thin plates of air, as in the phss-'
BOmena of coloured ringSj*

■4. I found that a mixture of chlorine and
hydrogene acted more rapidly upon each other,
coHibining without explosion, when exposed to

[ 212 ]

the red rays, than when placed in the violet
rays ; but that solution of chlorine in water,
became solution of muriatic acid most rapidly,
when placed in the most refrangible rays in the
spectrum.

I found that the puce-coloured oxide of lead
when moistened, gradually gained a tint of red
in the least refrangible rays, and at last became
black, but was not aiTected in the most refran-
gible rays ; and the same change was produced
by exposing it to a current of hydrogene gas.
The oxide of mercury procured by solution of
potassa and calomel, exposed to the spectrum,
was not changed in the most refrangible rays,
but became red in the least refrangible rays,
which must have depended upon its absorbing
oxygene. The violet rays produced upon
moistened red oxide of mercury, the same ef-
fects as hydrogene gas.

6. The general facts of the refraction and
effects of the solar beam offer an analogy to the
agencies of electricity. In the voltaic circuit the
maximum of heat seems to be at the positive
pole where the power of combining with oxy-
gene is given to bodies, and the agency of ren-
dering bodies inflammable is exerted at the op-
posite surface ; and similar chemical effects are
produced by negative electricity, and by the
most refrangible rays of the solar beam.

213 ]

7. In general, in nature, the efTects oF the
solar rays are very compounded. Healthy ve-
getation depends upon the presence of the solar
beams, or oF light, and whilst the heat gives
fluidity and mobility to the vegetable juices,
chemical effects likewise are occasioned, oxy-
gene is separated from them, and inflammable
compounds formed. Plants deprived of light
become wliite, and contain an excess of sac-
charine and aqueous particles ; and flowers owe
the variety of their hues to the influence of the
Golar beams.

Even animals require the presence of the
rays of the sun, and their colours seem mate-
rially to depend upon the chemical influence
of these rays ; a comparison between the
polar and tropical annnaiS, ai id between the
parts of their bodies exposed, and those not
exposed, to iightj shev.'s the correctness of ihis
opinion.

IV. Of the JYature of the Motions or AJections
of radiant Matter.

1. Two hypotheses have been invented to
account for tlie principal operations of radiant
matter. In the first it is supposed that the,
universe contains a hishly rare elastic sub*
stance, which when put into a state oi itndiilaiiiin^
produces those eflects en our prgaus of sight.

[ 214 ]

wliicliccnststnte the sensations of vision, and rfie
other phaeaomena occasioned by solar and ter-
restrial rays. In the second it is conceived that
particles are crdlted or sent off from luminous or
lieat-raaking bodies with great velocity, and
that they produce their effects by coinniuoi-
cating tlieir motions to substances, or by enter-
ing into themj and changing their composition.'

2. The first of these siipposidoos was adopted
by Hooke, Huygens. and Euler; — the second
by Newton, and the philosophers of the New-
tonian School. Many of the pbcsnomena may
be accounted For by either hypothesis, but the
Newtonian doctrine applies much more happily
to most of the facts discovered respecting
the modifications of ligiit by double refraction
snd reflection. Indeed it does not seem possible,
as Newton has shewn, to account for the cir-
cumstance ; that a ray which has suffered
extraordinary refraction in passing through
one crystal, should suffer ordinary refraction ip.
massing in another direction, through another
like crystal, on the idea of the effect being a
mere undulation of an ethereal medium ; but
it may be explained by supposing the rays to
consist of particles endowed with rectilineal mo-
tion, and possessed of a certain polarity, that is,
parts attractive with respect to some surfaces of
the crystal^ and repulsive with respect lo^other^j

[ 215 ]

5. M. Mains has supposed, in his ingenious
speculations on these remarkable phcenomena,
that the molecules producing light, are pos-
sessed of three rectangular axes, of which one
is always in the direction of the ray, and the
other two are made by the influence of the
repulsive forces exerted by the crystalline
raediura, perpendicular to the direction of these
forces ; and such a form, and sueh an effect
would correspond with the idea of the luminous
particles being octaedrons.

4. As the coloured rays separated by the
prism, bear the same relation to double refrac-
tion, that direct light bears, it follows that the
polarity of the diiferent particles must be of the
same kind, and this is what might be expected.
The same crystalline substance always affects
the same primary forms. When a tourmaline
is broken into pieces, the pieces are found
to possess similar electrical powers to the ori-
ginal crystal, and a large rhomb of calcareous
spar, easily breaks into a number of small
rhombs.

5. Newton has attempted to explain the dif-
ferent refrangibility of the rays of light, by
supposing them composed of particles differing
in size, and this hypothesis is not contradictory
to the idea of their being regular solids endowed
with similar polarities. The same great man

1

[ 216 ]

has put the query whether h'ght and common
matter are not convertible into each other ; and
adopting the idea that the pbacnomena of sen-
sible heat depend upon vibrations of the parti-
cles of bodies, supposes that a certain Intensity
of vibrations may send ofif particles into free
space, and that particles in rapid motion in
right lines, in losing their own motion, may
communicate a vibratory motion to the particles
of terrestrial bodies.*

* The views of Newton are so clearly developed in the
fallowing passages, and they are 40 much connected with the
refined philosophy of Chemistry, that the reader probably
will require no apology for the insertion of them in a note.

Quere. 29. Are not . the rays of light very small bodies
emitted from shining substances ? Foi; such bodies will pass
through uniform mediums in right lines, without bending into
the shadow, which is the nature of the rays of light. They
will also be capable of several properties, and be able to con-
serve their properties unchanged, in passing through several
mediums wnicn is another condition of the rays of light-
Pellucid substances act upon the rays of hght at a distance,
in refracting, reflecting, and inflecting them ; and the rayg
mutually agitate the parts of those substances at a distance
^ar heating them ; and this action and re-action at a distance,
wry much resembles an attractive force between bodies. 1^
refraction be performed by attraction of the rays, the sines of
incidence must be to the sines of refraction in a given pro-
portion; as we shewed in our principles of philosophy, and
this rule is true by experience. The rays of light in going out
of a glass into a vacumn, arc bent towards the glass ; and if
they fall too obliquely on the vacuum, they are bent back-
wards into the glass, and totally reflected ; and this reflection
Cannot be ascribed to the resistance of an absolute 'vacuum.

I 217 1

6. As particles of any gaseous medium wlien
put into a state of unduiatory motion are capable

but mu9t.be caused by the power of the glass attracting tlie
rays at their going out of it into ihetiacuum, and bringing them
back. For if the farther surface of the glass be moistened witk
water, or clear oil, or liquid and clear honey, the rays which
would otherwise be reflected, will go into the water, oil, or
honey, and therefore are not reflected before they arrive at
the farther surface of the glass, and begin to go out of it. But
if they go out of it into a vacuum, which has no attraction ts
balance that of the glass, the attraction of the glass either
bends and refracts them, or brings them back and reflects them«
And this is still more evident by laying together two prisms
of glass, or two object-glasses of very long telescopes, the one
plain, the other a little convex, and so compressing them that
they do not fully touch, nor are too far asunder. For the
light, which falls upon the further surface of the first glass*
where the interval between th,e glasses is not above the ten
hundred thousandth part of an inch, will go through tha*
surface, and through the air, or vacuum between the glasses,
and enter into the second glass, as was explained in the first,
fourth, and eighth observations of the first fart of the second
Book. But if the second glass be taken away, the light, which,
goes out of the second surface of the first glass into the air,
or vacuum, will not go on forwards, but turns back into the
Tst glass, and is reflected ; and therefore it is drawn back by
the power of the first glass, there being nothing else to turn
it back. Nothing more is requisite for producing all the va-
riety of colours, and degrees of refrangibility, than that the
rays of light be bodies of different sizes ; the least of whichi
may make a violet, the weakest and darkest of the colours*
and the mure easily diverted by refracting surfaces from the
light course ; and the rest as they are bigger and bigger, may-
make the stronger and more lucid colours, blue, green, yel-
low, and red, and be more and more difficultly diverted.
JSfothing more is requisite for putting the rays of light intQ

[ 218 ]

of producing the sensation of sound by actiog
upon the auditory organsj so it may be con-
fits of easy reflection and easy transmission, than that they
be small bodies, which by their attractive powers, or some
other forces, stir up vibrations in what they act upon ; which
vibrations being swifter than the rays, overtake them succes-
sively, and agitate them, so as by turns to increase and de-
crease their velocities, and thereby put them into those fits.
And lastly, the unusual refraction of island crystal, looks
very much as if it were performed by some kind of attractive
virtue, lodged in certain sides, both of the rays, and of the
particles of the crystal, and not in their other sides; for
\vere it not for some kind of disposition or virtue lodged in
some sides of the particles of the chrystal, and which
inclines and bends the rays towards the coast of unusual
refraction ; the rays which fall perpendicularly on the
crystal, would not be refracted towards that coast, rather
than towards any other coast, both at their incidence, and at
their emergence, so as to emerge perpendicularly, by a con-
trary situation of the coast of unusual refraction, at the second
surface ; the crystal acting upon the rays, after they have
passed through it, and are emerging into the air, or, if you

.please, into a mcmim. And since the crystal, by this <lispo-
sition, or virtue, does not act upon the rays, unless when
one of their sides of unusual refraction, looks towards that
coast ; this argues a virtue or disposition in those sides of the
rays, which answers to, and sympathises with that virtue or
disposition of the crystal, as the poles of two magnets answer
to one another. And as magnetism may be intended and re-
mitted, and is found only in the magnet and in iron, so this
virtue of refi'acting the perpendicular rays is greater in island
crystal, less in crystal of the rock, and is not yet found in
other bodies. I do not say that this virtue is magnetical; it

' seems to be of another kind ; I only say, that whatever it be,
it is difficult to conceive how the rays of light, unless they be
bodies, can have a permanent virtue in two of tlifiir sid«s

[ S19 ]

ceivedj that certain particles or aggregates of
particles from any matter moving with great and
equal velocity may occasion the sensations o£
vision, and the lother effects of the solar beams;
and the dilEculty of refracting terrestrial radianfe
heat, may be conceived to depend upon the
greater size of the aggregated particles ; undk
according to the Newtonian hypothesis, any
matter moving with considerable quickness m
right lines may be conceived capable of com"*
mtmicating an expansive motion to the particles
of bodies.

7. If specific highly rare imponderable fluids
be assumed, to account for the phjenomena, as
many must be adopted, as there are different
series of efiects produced by different rays.
There must be a matter of violet light, a matter

which is not in their other sides ; and this without a,ny regard
to their position to the space, or medium, through which they
pass" Optics.

May not the experiments of Dr. Young, Phil. Trans. 1804-,
page 2, which he considers as proving that homogeneous light,,
at certain equal distances, in the direction of its motion, is
possessed of opposite qualities capable of neutralizing each,
other, and of extinguishing the light when they happen to be
united ; be explained on the idea of attractive poles in oppo-
site sides of ihe {^articles of light. That able philosopher con-
sidered them as favourable to the theory of undulation ; but
if the attractions of other matter can destroy the motions of
light, as in the case of its action on black bodies, may not the
same result be produced by the attractions of its particles for
each other ?

[ S20 ]

of blue light, and so on : and likewise a deoxi-
dating ethereal matter, a calorific solar matter,
and a calorific terrestrial matter, which is very-
contradictory to the usual simplicity of" causes
observable in the oeconomy of things ; and the
idea likewise is rendered improbable, by ex-
periments on solar phosphori. When a
mixture of calcined oyster shells, and sulphur,
that have been heated together, is exposed
to the solar rays, it forms a good solar phos-
phorus, it becomes luminous, and continues
so for some minutes in the dark : and to which-
ever of the prismatic rays it be exposed, its
light is always the same, pale yellow. It is easy
to explain the phaenomenon, on the idea that
vibratory motion is communicated to particles
of the substance by the rays, in consequence of
which, some of its own particles are slowly sent
ofF, or that the particles have been formed into,
new aggregates in consequence of the attraction
of the substance ; but if light be supposed spe-
cific in its kind, and absorbed and emitted ;
then when the phosphorus is exposed to blue
rays, blue rays alone ought to be emitted, which
is not the case.

8. Many authors have written of the combi-
nations of light and heat ; but from the views
that have been developed, even taking the
Newtonian theory of emission for granted, it is

[ 22i ]

evident tliat such combinations are merely hy-
pothetical. When the solar rays are absorbed^
as it is called, by a black body, it must be con-
ceived, on this theory, that their motion is
communicated to the particles of the body, but
whether they adhere to it, or are thrown off in
new aggregates, as radiant heat, cannot well be
discussed, For we have no means accurate
enough to determine whether in such cases
there is an increase of weight; and this is the
only test to be depended upon, of true chemical
combinationj or of mechanical mixture.

The fire produced in a number of che-
mical processes, particularly in combustion,
on the Newtonian view, may be ascribed to
particles sent into free space, in consequence of
the repulsion exerted by other particles at the
moment of their entering into chemical union.
Any solid bodies may be made to emit light,
when exposed to a blast of air very hot, though
not luminous ; the light is always of the same
kind, and this circumstance is favourable to the
idea of the possibility of the conversion of com-
mon matter into radiant matter.

Many phsenomena which have been attributed
to combined light, appear to be electricalj or to
be merely the effect of the ignition of the sub-
stances, for whenever heat rises beyond a cer-
tain degree, bodies become luminous ; pieces

quartz rubbed together are rendered electrical ;
and by percussion or friction any hard bodies,
may be intensely healed.

During the putrefaction of certain animal
and vegetable substances, light is emitted ; and
this is no more difficult to account for, than the
feeat produced during similar operations.

The light emitted by certain living insectsj
appears to depend upon ihe secretion of a sub*
stance very easy of decomposition: and any
chemical change may be supposed adequate to
the production of light.

It has been sometimes supposed that a specific
imponderable substance, capable of producing
light, is GOhtained in oxygene gas ; and it has
been also imagined that such a substance exists
in inflammable bodies ; but the facts are contra-
dictory to the hypothesis. Iron, when heated
to whiteness, burns with amazing brilliancy ifi
oxygene gas, throwing off sparks intensely
luminous ; but when heated to^600° Fahren-
heit, it combines slowly with the oxygene^
producing heat without light; the chemical
change is of the same nature in both cases ; the
only difference is in its rapidity and energy*

9. The later investigations on light, teach US
that there is still much to learn with respect to
the affections and motions of radiant matter ;
snd this subject, when fully understood, pro*

mises to connect together cbemical and meclia-
nical science, and to offer new and more com-
prehensive views of the corpuscular arrange-
ments of matter.

In radiant matter, the particles act almost
independently of the common laws of attraction ;
and by prismatic refraction, the difference of
their actions is determined, and it seems pro-
bable that the relations of the different particles
to the crystalline arrangements of matter, will
be found connected with those powers which
they possess analogous to electrical qualities.

If that sublime idea of the ancient Philoso-
phers which has been sanctioned by the appro-
bation of Newton, should be true, namely, that
there is only one species^f matter, the different
chemical, as well as mechanical forms of which
are owing to the different arrangement of its
particles, then a method of analysing those forms
may probably be found in their relations to
radiant matter. Newton supposed that the lumi*
nous particles at the violet end of the spectrum
w^ere smallest in size, and those at the red end,
largest in size, and those producing the inter-
mediate colours, intermediate. On this idea,
the calorific invisible particles would be the
largest in the solar beam, and the calorific
particles emitted by terrestrial bodies, may
be imagined of still greater size, so as to be

[ 224 1

iacapable of passing'"tIirough the pores of dense
transparent media. The rays at the red end of
the spectrum in their chemical powers, tend to
burn bodies, or to combine them with oxygene ;
those at the opposite end tend to restore in-
ftamraabih'ty to bodies ; and negative electricity
which exercises the same function, produces
hydrogene gas from water; and this is the
lightest chemical element in nature, and may
be conceived to be composedj on the corpuscular
hypothesis, of the smallest particles.

10. The idea that light is not a specIHc fluid,
is confirmed by some practical results relating
to the oeconomy of light. Count Rumford has
lately shewn that the quantity of light emitted
by a given portion of inflammable matter
in combustion, is proportional in some high
ratio to the elevation of temperature ; and that
a lamp having many wicks very near each other,
so to communicate heat, burns with infinitely
more brilliancy than the Argand's lamps in
common use.

[ SS5 ]

DIVISION III.

OF EMPYREAL UNDECOMPODNDED SUB-
STANCES, OR UNDECOMPOUNDED SUB-
STANCES THAT SUPPORT COMBUSTION,
AND THEIR COMBINATION WITH EACH
OTHER.

I. General Observations,

1. It has been mentioned that almost all cases
of vivid chemical action are connected with the
increase of temperature of the acting bodies,
and a irreater radiation of heat from them ; and
in a number of instances, light is also produced,

see p. 92, and 164-

The strength of the attraction of the acting
bodies determines the rapidity of combination,
and in proportion as this is greater, so likewise
is there more intensity of heat and light. In the
phlogistic doctrine of chemistry, all changes in
which heat and light are manifested, were ex-
plained by supposing that the acting bodies con-
tained the principle of inflammability ; in the an-^
tiphiogistic doctrine, most of them have beea
accounted for by imagining the position or trans-
fer of oxygene : but all the later researches seem
to shew that no peculiar substance, or form of
YQl,. I.

[ 526 ]

matter is necessary for the effect ; that it is a
general result of the actions of any substances
possessed of stroqg chemical attractions, or dif-
ferent electrical relations, and that it takes place
in all cases in which an intense and violent
motion can be conceived to be communicated
to the corpuscles of bodies.

2. Many bodies which have not yet been
decompounded, and which cannot well be con-
ceived to contain oxygene, produce heat and
light by their mutual chemical action- — such are
somemetaUicsubstaoces, potassium, forinstance,
in combining with arsenic and tellurium ; and
sulphur and certain metals become ignited
during their union. In naming a class of bodies
by their relations to combustion, or to their effi-
cacy in producing the phenomena of fire, it is
only intended to signify that the production of
Jieat and light is more characteristic of their ac-
tions, than of those ofany other substances ; and
ihey are likewise opposed to all other undecom-
pounded substances by their electrical relations,
being always in voltaic combinations attracted
to, or elicited from the positive surface ;
>vhereas all other known undecompoundecj
substances are separated at the negative surface.
Only two undecompounded empyreal substan-
ces have been as yet discovered. They wii| b%

I 227 i

described, and tlieir actions on each other dis-
cussed in the two followins: sections.

n. Of ox/gene Gas.

1. Oxygene gas v^^as discovered by Dr. Priest-
ley,in August, 1774. To procure it, a quantity of
manganese (a mineral substance found in abun-
dance near Exeter, and in many other places)
is introduced into a glass retort furnished with
a ground stopper, a quantity of oil of vitriol
{sulphuric acid) sufficient to moisten the
manganese, is added, and they are mixed toge-
ther by means of a glass rod ; the bottom of the
retort is then gently heated by means ofa lamp,
and the extremity of its neck introduced under
an inverted cylinder filled with water in the hy-
dro-pneumatic apparatus,* Globules of gas will
soon rise through the water ; the first portions
collected must be thrown away, being princi-
pally the common air contained in the retort ;
when a quantity equal to the capacity of the
retort has been thus disposed of, the remainder
may be preserved for use.

There are many other modes of obtaining
oxygene gas ; the same manganese heated to
redness in andiron tube, such as a gun-bar-
rel, the touch-hole of which is closed, will
afibrd a considerable quantity of the sub-
• See Plate. IV. Fig. 23,

f f28 ]

stance, which may be collected by means of a
tube fastened into the neck of the barrel, and
having its extremity in the hydro-pneumatic

fipparatos.*

Nitre heated strongly in a porcelain retort,
gives off oxygene gas : puee-coloured, or red
oxide of lead offers a similar result ; and from
any of the salts called hyperoxymurlates,
oxygene is procured by a dull red heat ; a re-
tort of glass may be employed in the process ;
^nd a charcoal fire in a small chaffin2;-dish.

100 grains of the hyperoxymuriate ofpotassa,
alford about II4 cubical inches of oxygene
gas, under common circumstances.

Tiie oxygene gas procured from nitre and ihe
snetallic substances above mentioned, is mixed
with larger or smaller quantities of other per-
manent gaseous matter; the gas from hyperoxy-
muriate of potassa is iree from such adulterationj
and when collected over mercury, contains no-
thing but aqueous vapour, from which it may
be purified by means of the salt called dry mu-
riate of lime, or by sticks of common potash.
The elastic fluid from nitre contains more foreign
gaseous matter than that from the metallic oxides,
The gas from manganese and sulphuric acid,
when collected in the mercurial apparatus,
seldom affords more than -3^ of adulteratior?,
* See Plate IV. 2^

t 229 ]

when collected over water, it is mixed ■witfi
from -Jq- to -3^! consequence of mixture with
the common air expelled from the water.

The degree of purity of oxygene gas pro-
cured in these modes, is easily ascertained by
fillina; a small curved tube closed at one end,
with mercury, and passing into it some of the
dry gas, so as to occupy about ^ of its capacity,
■Which is measured ; a bit of phosphorus in the
proportion of half a grain to a cubical inch of
gas, is introduced and made to pass into the
curved part of the tube ; the phosphorus is in-
flamed by the application of the heat of a spirit
lamp ; at the moment of the expansion of the
gas, the open extremity of the tube is closed
under the mercury by the finger, and heat is
applied till no light can be perceived in the
tube ; when the tube is cool, the finger is taken
off. The mercury will instantly rise into the
lube ; all the oxygene will have been absorbed,
and the gas remaining, when measured and
compared with the original quantity, will in*
dicate the impurity.

2. Oxygene gas is distinguished from all
other gaseous matter by several important pro-
J)erties.

Inflammable substances turn iti it tiiider the
same circumstances as in corarnon air, but with
infinitely greater vividness*

[ 230 3

If a taper, the flame of which has been ex-
tinguished, the wick only remaining ignited,
be plunged into a bottle filled with it, the flames
will be instantly rekindled, and will be very
brilliant, and accompanied by a crackling
noise.

If a steel wire, or thin file, having a sharp
point, armed with a bit of vfood in inBamma-
tion, be introduced into a jar filled with the
gas, the steel will take fire, and its combustion
will continue producing a most brilliant phe-
nomenon.

The specific gravity of oxygene gas has been
already referred to, page 112, it is to that of
hydrogene gas, as 15 to 1 ; 100 cubical inches
under an atmospherical pressure equal to that
of 30 inches of mercury, and at the temper-
rtcure of 60'' Fahrenheit, weigh about 34
grains. Its power of refracting light, is stated
by Biot and Arago to be to that of hydro-
gene, nearly as 195 8 to 1000. Its capacity for
heat, according to Br. Crawford, is nearly a«
4.7 to 21.4.

Oxygene gas is slightly absorbable by water.
From Dr. Henry's experiments, it appears that
this fluid takes up _V of its bulk at 60° Fah-
renheit, whatever be the density of the gas.

Oxygene gas is respirable ; a small animal
confined in a jar filled with this gas, lives four

[ £31 ]

01' five times as long as in an equal quantity of
common air hence it has been called vital

air.

3. The proportion in which oxygene gas
unites to bodies, has been referred to, page 113,
and the number representing it may be consi-
dered as 15; various elucidations of the cor-
rectness of this conclusion, will be found in
the following pages.

4. Oxygene gas forms the most important
part of our atmosphere. It is easy to prove this
by many very simple experiments.

If phosphorus be inflamed in a tube half
filled with atmospherical air, in the same man-
ner as in the experiment for ascertaining the
purity of oxygene, a quantity of elastic matter
will be absorbed equal to about one fifth of the
volume of the confined air, and the same sub-
stance will be produced as that formed by
burning phosphorus in oxygene: the remain-
ing elastic fluid will not support flame, and
animals will not live in it ; it is called azote or
iiitrogene gas ; and if four parts of it be mixed
wiih about one part of pure oxygene gas, they
constitute a mixture resembling exactly atmos-
pheric air. Tiiat the oxygene obtained artifi-
cially is the same chemical substance as that ^
found in the air, is proved by the phsenomena of
the calcination of mercury. If running mercury

[ ]

he preserved in a heat at which it boils slowly^
in a retort, the beak of which is plunged in
mercury, and the process be continued for some
days, there will be a gradual diminution of the
air, and after a certain time, the remainder will
not support flame, and a part of the mercury
will be found converted into a red powder. It
will have gained in weight, as much as the air
has lost; and the red powder, if heated to ig-
nition, will give off a quantity of oxygene, that,
added to the residual elastic substance, will re-
constitute common air and it will be restored to
the state of mercury. And this oxygene, if a
•part of it be compared with the oxygene procured
in other modes from mineral substances, or ar-
tificial compounds, is found in no respect differ-
ent ; its specific gravity, refractive power, and
t:hemical properties, are precisely identical.

There have been several substances proposed
for ascertaining with facility the quantity of
oxygene in air ; they have been called eudio-
metrical substances ; and the instruments in
which they have been employed, are named
eudiometers. The solution obtained by water
from sulphur and pearl ashes, or sulphur and
lime that have been fused together, slowly ab-
sorbs oxygene ; a solution of tin in muriatic
acid, has a similar property ; and likewise so-
lotions of iron, into which nitrous gaa has beeii

t $^S3 ]

passed till they become coloured. A tube
of glass graduated to 1 00 parts, forms a good
eudiometer ; and when filled with air, it is
plunged into any solution that will absorb oxy*
gene, and suffered to remain there, till the
process is complete.

It was formerly supposed that there are great
differences in the quantity of oxy gene in air,
in different places, and at different times ; but
all late researches shew that .this opinion is
erroneous.

Air, analysed in different quarters of the
globe, in cities, and in the country, on sea and
land, has been found not perceptibly different
in composition; the accurate proportions of
oxygene and azote are 21 and 79.

It has been shewn by the experiments of Dr,
Priestley, Mr. Dal ton, and M. Berthollet, that
different elastic fluids have a tendency to rapid
equable mixture, even when at rest, and exposed
to each other on small surfaces only ; and the
mixture of the parts of the atmosphere is con-
stantly assisted by winds, by currents of air,
and by all the motions taking place on the
surface of the earth4

5. In all processes of combustion in the at-
mosphere, oxygene is either fixed in the com-
-bustible body, or it dissolves it, or forms a new
compound with it, Jn respiration, as will be

[ ]

ftiore folly explained in the last part of tlik'.
work, the volume of air is not changed : but a
part of its oxygene disappears, and an equal
bulk of carbonic acid gas is found in its place.

As the constitution of the atmosphere con-
stantly remains the same, it is evident that there
must be some processes in nature, by which a
quantity of oxygene is produced equal to that
consumed. One principal cause of the renova-
tion of oxygene appears to be in the process of
vegetation ; healthy plants exposed in the sun-
shine, to air containing small quantities of car-
bonic acid gas, destroy that elastic fluid and
evolve oxygene gas ; so that the two great classes
of organized beings are dependent upon each
other. Carbonic acid gas, which is formed in
many processes of combustion, as well as irt
respiration, if not removed from air, by its
excess would be deleterious to animals, but it
IS a healthy food of vegetables ; and vegetables
produce oxygene, which is necessary to the
existence of animals, and thus this part of the
teconomy of nature is preserved, by the very
functions to which it is subservient ; and the
order displayed in the arrangement, demon-
states the intelligence by which it was designed*

6. No other forms of matter have been pro-
duced from oxygene by any processes to which
it has been subiiiitted ; but it readily eatei»

[235]

into combination, and no substance is mora
active as a chemical agent. It is known to be a
constituent part of most of tlie acids and earths,
and of ail the alkalies except one, and-the his-
tory of its compounds, forms the most extensive
and important part of modern chemistry.

Its operations, as w'lli be seen hereafter, are
Connected with many of the Arts ; with the
processes of bleaching, dyeing, colour-making,
and metallurgy ; and in its various applications
to the production of fire, it is absolutely essen-
tial to culdvation, and to the comforts and ea-
joyments of social life.

In the phsenomena of nature, it occasions a
wonderful diversity of effects. It is active in
most of the changes taking place on the surface
of the globe, and its constant tendency is to
unite different substances in forms adapted for
the purposes of organized life.

n. Chlorine, or oxjmuriatic Gas.

\. This elastic substance was discovered by
Scheele in 1774. It maybe procured in the
hydro- pneumatic apparatus, by a process very
similar to that first described in the last section
for procuring oxygene gas, but the manganese
is to be mixed with common salt, and the oil of
vitriol diluted with an equal quantity of watei%
The best proportions are three parts of common

E .^36 ]

salt in weight, one part of manganese finely'
powdered, and two parts of oil of vitriol ;
Instead of manganese, red oxide of mercury, or
puce-coloured oxide of lead may be used, and
instead of the common salt, and oil of vitriol,
a solution of muriatic acid in water (spirits of
salt. C.)

S. Chlorine is of a yellowish green colour^
and it is this property which suggested its
name.* Its odour is extremely disagreeable. It
is not capable of being respired, and even when
mixed in very small quantities, with common air,
renders the air extremely pernicious to the lungs^

Its specific gravity is to that of hydrogene^
nearly as S3.5 to 1, and 100 cubical inches of it
weigh at mean temperature and pressure between
76 and 77 grains.

It is absorbable to a certain extent by water:
at the temperature of 60° Fahrenheit, water
dissolves about double its volume, and acquires
a strong acrid taste, and a disagreeable smell.

When an inflamed taper is introduced into
a phial filled with it, the light continues, but
of a dull red colour, and a dark carbonaceous
smoke rises from the flame.

Many of the metals introduced into it in,
thin filaments, or leaves, or powder, take fire,
and burn spontaneously at common tempera-

1

[ 237 3

tares ; such are copper, tin, arsenic, zinc, anti-
mony, and the alkaline metals.

Phosphorus burns in it spontaneously, with
a pale white light, producing a white volatile
powder.

Sulphur melted or sublimed in it, does not
burn, but forms with it a volatile red liquor.

The gas does not change by any action of
heat or cold; but its aqueous solution freezes
more readily than water, n^^-ifiely at about 40"^
Fahrenheit. i
When freed from vapour by muriate of lime,
the gas does not act upon perfectly dry sub-
stances tinged with vegetable colours ; but when
moiskire is present in the gas or the coloured
bodies, their colours are speedily destroyed,
they are rendered white, or brought to a dull
yellow ; and this last tint is almost the only
one not changed by the combined action of
water and chlorine.

3. Chlorine and oxygene are capable of
existing in combination, and they form a pe-
culiar gaseous matter. They do not unite, whea
mixed together, but when existing in certain
solids, they may be detached in union.

To make the compound of chlorine and oxy-
gene, hyperoxymuriate of potassais introduced
into a small retort of glass ; and twice as much
muriatic acid as will cove^- it, diluted with an

I m ]

equal volume of water. By the application of
a gentle heat, the gas is evolved, and it must be
collected over mercury,

I discovered this elastic substance in its pure
form in January 1811, and gave to it the name
of EuchJorine,* from its bright yeiiow-green.
colour.

Its tint is much more lively than that of
chlorine, and more inclined to yellow.

Its smell is very?>dilFcrentj being not unlike
that of burnt siio-ar.

It is not respirable.

It is soluble in water, to which it sives a
lemon colour, water takes up 8 or 10 times its
volume.

Its specific gravity is to that of hydrogene,
nearly as 33 to 1. 100 cubical inches weigh at
mean temperature and pressure between 74 and
75 grains.

It must be collected and examined with ereat

O

care, and only in small quantities at a time ; a
very gentle heat causes it to explode, sometimes
even the heat of the hand ; and its elements
separate from each other with great violence,
producing light.

From the facility with which euclorine de-
composes, it is not easy to ascertain the action
of combijstible bodies upon it. None of the

C 239 ]

inetals that burn in chlorine, act upon this ga?
at common temperatures ; but when the oxy-
gene is separated, they then inflame in the
chlorine. It is easy to witness this. Let a little
Dutch foil be introduced into a bottle filled with,
euchlorine, it will undergo no change, and
will not even tarnish. Let a heated glass tube
be applied to the gas in the neck of the bottle
a decomposition will take place, and the oxy-
gene and chlorine will be detached from each
other, and at the same moment the foil will
inflame, and burn with great brilliancy.

Chlorine is rapidly absorbed by mercury ;
JEuchlorine has no action upon it, and chlorine
may be separated from euchlorine, by agitation
over mercury, and the last obtained pure.

When phosphorus is introduced into euchlo-
rine, it is instiintly decomposed, and the phos-
phorus burns as it would do in a mixture of Q,
parts in volume of chlorine, and 1 part of
oxygene.

The inflamed taper, and inflamed sulphur,
instantly decompose it, and exhibit the same
phsenomena as in a mixture of 2 parts of chlo-
rine, and 1 part of oxygene.

That the gas is actually composed of these
elements, is shewn by causing it to detonate in
a glass tube over pure mercury. It looses its
bnlliant colour, and becomes chlorine and

[ 240 3

oxygene. 50 parts treated in this way, expmcl
so as to become about 60 parts, which consist
of 40 parts of chlorine, and 20 parts of oxygene.
When euchlorine freed from water, is made
to act upon dry vegetable colours, it gradually
destroys them, but first gives to the blues, a
tint of red; from which, and its absorbability
by water, and the taste of its solution, which is
strongly acrid approaching to sour, it may be con-
sidered as approximating to an acid in its nature.

4' The proportion in which chlorine combines
with bodies, may be learnt from the decompo-
sition of euchlorine ; the oxygene in which
is to the chlorine, as 15 to 67 in weight. If eu-
chlorine be considered as consisting of one
proportion of oxygene to one of chlorine, then
67 will be the number representing chlorine,
which is most convenient, as beins: a whole
number. If euchlorine be supposed to contain
two proportions of chlorine and one of oxy-
gene, then the number representing chlorine,
will be S3 5. It will hereafter be shewn that
whichever of these data be assumed, the rela-
tions of the number will harmonize with those
gained from various other combinations.

5. Scheele considered chlorine as an element
of the muriatic acid, and hence called it de-
phlogisticatqd marine acid. By that chemist,
it was regarded as an undecompoiinded body.

[ 241 ]

Lavoisier and Berthollet asserted that it was
a compound of muriatic acid gas, and oxygene.
This idea is now universally given up ; but
some Chemists in France and Scotland, con-
ceive that it is a compound of oxygene, and an
unknown body, which they call dry muriatic
acid. The weight of chlorine, its absorbability
by water, its colour, and the analogy of some
of its combinations to bodies, known to contain
oxygene, are arguments in favour of its being
a compound ; and it is possible that oxygene
may be one of its elements, or that oxygene
and chlorine are similarly constituted. I
have made a number of experiments with the
hopes of detecting oxygene in it, but without
success ; none of its compounds with inflam-
mable bodies or metals will afford this prin-
ciple ; charcoal intensely ignited in it, un-
dergoes no change, nor is it altered by the
strongest powers of electricity. Should oxygene
ever be procured from it, some other form of
matter, possibly a new one, will at the same
time, be discovered, as entering into its consti-
tution, and till it is decompounded, it must be
regarded, according to the just logic of che-
mistry, as an elementary substance.*

* M. M. Gay Lussac, Thenard, [and Curaudau, since
1808, have laid claim to the ideas of oxymuriatic gas being
a, simple body, and of muriatic acid gas being composed of

VOL.1. R

6. Chlorine has never been found pure in
nature ; but exists in many compounds, par-
ticularly in common salt, as is evident from the
mode of its production from that substance. It
is a substance of considerable importance in its
relation to the art of bleaching, an application
first made by the sagacity of M. BerthoUet.

In the ancient process of bleaching, the cloths
of linen and cotton, after beina; treated with al-
kaline lixivia, to free them from resinous and
oily matters, and in some cases with very di-
luted oil of vitriol, to cleanse them from stains
produced by iron, were exposed upon grass to
dew and air, and some weeks, or even months,
were required to give them their perfect
whiteness.

By a warm solution of chlorine in water,
they are bleached in a very short period ; but
their texture is injured ; for at the same time
that oxygene is added to the colouring matters,
muriatic acid gas is formed and dissolved in the
water, which corrodes the vegetable fibres.

The gas has been condensed in alkaline
lixivia, and in lime water. The substance called

this substance and hydrogene. But these opinions were started
by the illustrious Discoverer of the gas, in 1774. In th«
papers in the Philosophical Transactions in which I have en-
deavoured to shew that ii is a peculiar acidifying and solvent
principle, I have merely followed and extended his views, and
I referred to thpra in the first paper I published on the subject.

[ m ]

tj§iymutiate of lime is commonly used for
bleaching ; but though the solution of this suhi-
stance does not injure so rtiuch as that of the gaSj
yet it tends to weaken the texture of linen.

I have found that the fluid produced by the
condensation of the gas in water containing
liiagnesia diffused through itj bleaches without
injuring the vegetable fibre. It acts much more
slowly and gradually, than any of the other com-
pounds employed for the same purpose, and has
been applied at my suggestion in Ireland, within
the last few months,* with success, in whitening
printed calicos, and when properly used, it does
not destroy even reds or yellows fixed by mor-
dants. Magnesia may be easily procured from
sea-water, or from the residual liquor of salt
works ; and there is a probability that this new
bleaching fluid may, at no very distant period,
come into common use.

M. Berthollet supposed that chlorine de-
stroyed colours by parting with its oxygene ; the
new experiments shew that the Oxygene is de-
rived from the water, which is decomposed by
double affinity; that of hydrogene for chlorine,
and of the; colouring matters for oxygene.

The salts which are called hyperoxymuriates,
and oxymuriates, are coirspounds of metallic

* By Mr. D%ffy of Dublin, a very enlightened calia®"
priiHer.

[ 244 ]

bodies with chlorine and oxygene ; and the
oxygene is held in them by a very weak at-
traction, and therefore is easily given off to
colouring or inflammable matters.

The great circumstance, in bleaching with
these compounds, is that the salt remaining
after the abstraction of oxygene, should not
act upon the linen ; linen boiled in a strong
solution of the salt called muriate of lime, the
substance remaining in the solution, when oxy
muriate of lime is used, I have found is consi-
derably weakened. Solution of muriate of
magnesia has no action of this kind, and there-
fore the new bleaching liquor can hardly be
injurious to the manufacture.

These general views respecting chlorine,
and the uses and mode of agency of the
combinations of chlorine and oxygene, will be
found to be confirmed by a number of state-
ments, to be given In the progress of this work.
Certain conclusions have been anticipated, — but
the most important application of chlorine
could not with propriety be separated from
its history; as an undecompounded body,
though depending upon its power of detaching
oxygene, which appears to be the true bleaching
principle from compounds.

[ 245 ]

DIVISION IV.

OF UNDECOMPOUNDED INFLAMMABLE OR
ACIDIFEROUS SUBSTANCES NOT METAL-
LIC, AND THEIR BINARY COMBINATIONS
WITH OXYGENE AND CHLORINE, OR
WITH EACH OTHER.

I, Preliminary Observations,

The bodies to be considered in this division,
are six, hydrogene, azote, sulphur, phosphorus,
carbon, and boracium or boron. Amongst
these, hydrogene is distinguished from all the
rest by very singular properties. Sulphur and
phosphorus are the most analogous to each
other. All these substances are capable of com-
bining with oxygene, and all except azote and
charcoal, with chlorine. They are separated
in Voltaic combinations, at the negative surface,
and in their electrical relations, as well as che-
mical powers, are opposed to oxygene and
chlorine.

[ 24Q ]

II. Hfdrogene Gas, or injlammable Air.

1 . This elastic substance was first examined
jn its pure form, by Mr. Cavendish, in 17 66.

It may be procured in the hydropneumatic
apparatus from zinc or iron filings, by means
of oil of vitriol diluted with 8 times its weight
of water ; a retort, or a bottle furnished with
a tube may be used ; no artificial heat is required
in the process. It may like\vise be produced
by passing steam over turnings of iron heate4
to redness in a guiu-barrel,

2. Hydrogene is distinguished from all other
gaseous bodies, by its extreme lightness. The
relation of its weight to that of oxygene and
air, has been already stated. 1 09 cubical inches
of it at mean temperature, and pressure, weigh
about two grains and a quarter.

It is very slightly absorbable by water ; that
fluid takes up only of its volume.

Hydrogene gas has no taste, a slight but dis-
agreeable smell. It is capable of being taken
into the lungs, but cannot be breathed by man,
for more than a minute. Small animals die in
it in a much shorter time.

When an inflamed taper is plunged into a
long narrow jar filled with hydrogene, and
opened in the atmosphere, it is extinguished ;

I 247 ]

but the gas takes fire, and burns in contact
with the atmosphere.

One part mixed with two or three parts of
air explodes violently by the action of an in-
flamed body, or an electrical spark.

3' Hydrogene gas, as has been stated, com-
bines with oxygene gas, and to this circum-
stance its inflammation in the air is owrng. If
the two gasses be pure, ivaier is the only result,
and the proportions are 2 of hydrogene to 15
of pxygene in weight, or 2 to 1 in volume.
The union may be effected by the electric
spark as described in page 104, over mercury,
or the hydrogene may be introduced into a ves-
sel full of oxygene through a narrow tube, by
means of pressure, and inflamed by electricity,
or the oxygene may be made to burn in the
hydrogene in a similar manner,* When a
stream of oxygene is thrown into a stream of
inflamed hydrogene, tlie heat produced is very
intense, and far exceeds the highest heat of our
furnaces, and may be used to fuce bodies,
intractable by any other fire raised by com-
bustion.

The nature of water may be shewn synthe-
tically as well as analytically.

It is separated into 2 of hydrogene in volume
p^d 1 of oxygene in the voltaic circuit; the
# See Plate V. fig. 25.

[ 248 ]

oxygene appears at the positive, the hydrogene
at the negative metallic surfaces ; and by means
of platina wires, hermetically sealed into glass
tubes, the products are collected.

When 10 grains of the metal called potas-
sium are added to about 2 grains of water in
a glass tube, there is a violent action, much
hydrogene is disengaged, and by heating the
results, the operation is completed. The same
effect is produced upon the potassium, as
would be produced by heating it strongly in
contact with a small quantity of oxygene, it
becomes united to oxygene, and its increase
of weight is in proportion to the weight of the
hydrogene, as 15 to S.

It will be needless to dwell upon the proper-
ties of water ; it is scarcely ever found in nature
pure, usually holding saline or gaseous matters
in solution. It becomes solid at 32° Fahrenheit
and elastic at 2 1 2°, and in the state of steam
has been applied for the production of the
most important mechanical effects in the steam
engine.

To describe the uses of water in the opera-
lions of nature, or to point out its applications
to the purposes of the arts, and common life,
v/ould demand a volume. Animals and vege-
tables depend upon it for their existence.
Water occupies nearly two-thirds of the sur-

[ 249 ]

face of the globe ; and whether existing in the
pcean united to salts, or in the atmosphere as
vapour, or poured down upon the surface as
rain, dew, hail or snow, or| collected in lakes,
rivers, and springs, its effects are constantly
connected with the order of the ceconomy of
our system.

4' Hydrogene and chlorine unite with still
more readiness than hydrogene and oxygene.
To make the combination, as has been stated
page' 111, it is only necessary to expose a mix-
ture of equal parts of the two gasses to common
day light, over dry mercury, or in a vessel
furnished with a stop cock previously exhausted.
In a certain time, the chlorine will have lost its
colour, and have combined with the hydrogene.
If the gasses have been freed from aqueous
vapour, there will be no notable condensation,
and the result is a peculiar elastic fluid, mwiatic
acid gas. By exposure to direct solar light as
has been stated before, they explode ; they
likewise explode by the electrical spark ; the
results in this case, as I have found, are the same,
1 in volume of hydrogene unites to 1 in volume
of chlorine, or 1 in weight to 33.5.

The nature of muriatic acid gas maybe proved
by analysis, as well as synthesis. If some pure
grain tin be kept melted for some time, in a
little curved tube containing muriatic acid gas

[ 250 ]

over dry mercury, the tin v^ili be converted
into the same substance as that produced by its
direct action upon chlorine, Llbavius's liquor,
and the hydrogene gas, when accurately mea-
sured, will be found to be eciual to one half the
volume of the muriatic acid gas.

Those persons who suppose chlorine to be a
compound of an unknoM^n body, and oxygene,
conceive muriatic acid gas to be a compound of
^ of its weight of water, and the same hypothe-
tical substance ; but as no oxygene has yet
been shewn to exist in chlorine, so no such
combined moisture has been proved to exist in
muriatic acid gas. It contains minute quantities
in the vapour of liydrated muriatic acid ; but
no water except this can be procured from it,
unless by substances that contain oxygene ; and
the quantity produced, is exactly proportional
(o the oxygene contained in the substance, and
the hydrogene in the muriatic acid gas, and the
other result is the same as the substance combined
with the oxygene would produce direclly' by lis.
action upon chlorine.

Five grains of red oxide of mercury, heated
to rednegSj gave oW a cubical inch, and i of
pxygene gas. Five grains of the same sub-
stance were made to act on muriatic acid gas
by a spirit lamp in a curved tube over mercury ;
pprrosiyq sublimate was forn^ed; and w<iter which

t 251 1

absorbed muriatic acid gas, and 5 cubical inches
pf muriatic acid gas discjppeared ; and of thesQ
4 cubical inches, and ^ at least, must have been
decomposed by the oxide of mercury, their
phlorine united to the metal, and their hydro-
gene to the oxygene ; and the additional half
a cubic inch, as wjil appear from the facts about
to be staled, is nearly the quantity that ought
to be absorbed by tjie water; the barometer ii>
this experiment gtpod at SO. 3 ; the thermometer
^t 54° Fahrenheit; Corrosive sublimate is pro*
(duced by the direct combination of mercury
and chlorine ; and the results of this experiment
can only be logically explained, on the idea
of muriatic acid gas being composed of hydroT
geiie and chlorine.

For the purposes of experiments, niuriatis:;
acid gas is procured by the action of oil of vi-
triol on certain salts, such as common salt, or
sal ammoniac. It rises without the application
of heat, when the substances are mixed toge-
ther ; a glass retort should be used with a ground
stopper, the salt should be in large pieces, no{;
in powder, and some bibulous paper should be
introduced irito the neck of the retort, to pre-
vent any fluiid acid from soiling the mercury,
pver which it must be collected-
Muriatic acid gas, instantly extinguishes
liamg. |t reddens dry litmus paper. Vyhei^

[ 252 ]

suffered to pass into the atmosphere, it pro-
duces a white smoke by uniting to the aqueous
vapour in the air. Its taste is intensely acid. Its
smell, pungent and disagreeable.

The specific gravity of muriatic acid gas is
to that of hydrogene, nearly as 17 to 1 ; 100
cubical inches of it weigh at mean temperature
and pressure, between 39 and 40 grains. Mu-
riatic acid gas is rapidly absorbed by water ;
at the temperature of 40° Fahrenheit, water
absorbs about 480 times its bulk of gas, and
forms solution of muriatic acid gas in water,
the specific gravity of which is 1,2109.

The table which follows, exhibits the quan-
tity of muriatic acid gas in solutions of different
specific gravities constructed after experiments
made at my request by Mr. E. Davy, in the
Laboratory of the Royal Institution,* the re-
sults of which I witnessed.

* 47.25 grains of water at 43° Fahrenheit, barometer
being at 30.2, absorbed 34.8 grains of gas, and formed a so-
Jution of specific gravity, 1.21, and the whole precipitated by
nitrate of silver, afforded about 132 grains of dry horn silver.

Again, 57.5 grains of water at 44°, barometer being 30.1,
gained nearly 38 grains by absorbing acid gas, and formed a
solutioH of specific gravity, 1.2.

Thermometer, 49° Fahrenheit ; barometer 29 ; 46.5 grains
of water by absorbing 13.4 grains of gas gained a specific
gravity of 1.114. The two last results, which are marked in
the table, agree with those gained by calculation from the
first experiment. When about 150 grains of the strongest
solution of muriatic acid in water, were mixed with distilled

[ 253 ]

At temperature 45."
Fahrenheit.

Barometer 30.

100 parts of solu-
tion of muriatic
acid gas in water of
specific gravity.

Of Muriatic acid
gas, parts.

1 1

1.21

il AO

42.43

1.20*

40.80

1.19

3a. 38

l.lb

3d.3o

1.17

if* i a 4

1. lo

32.i»2

1.15

o

o

30.30

1.14

28.28

1.13

C3

26.26

1.12

ain.

24.24

1. 11*

22.3

1.10

20.20

1.09

18.18

1.08

16.16

1.07

14.14

1.06

12.12

1.05

10.10

1.04

8.08

l.OS

6.06

1.03

4.04

1.01

2.02

water, both being at 63°, the temperature rose to 75" | so that
the real specific gravity ef solutions mixed with water, is
probably a little greater than the mean, though to no amount
that can interfere with the use of the table. To find the com-
position of an acid of specific gravity not marked in the table,
find the difference between the two specific gravities nearest
to it in the table d, and the difference between their quantities
of gas likewise the difference between the given specific
gravity, and that nearest to it, c, then d is to b:'.c:x which
added to the quantity of the lower specific gravity, is the
quantity of acid gas sought.

[ 2Bi ]

The compound of water, and muriatic adid
gas existing in vapour in muriatic acid gas,
alluded to page 189, is probably of the same
Constitution as the most saturated solution at
the same temperature, and at 45° must contain
57.57 per cent, of water ; but in common cases
the quantity of this vapour is too small to in-
fluence to any extent the results of experiments
on muriatic acid gas; fori found that 200 cubical
inches of gas at 75° passed slowly through a thin
tube of glass cooled to 10° below 0 of Fahrenheit;
did not increase its weight ^ %^^^^) but

the deposition of fluid was verydistinct.

4. The number representing hydrogene, as
is evident from the details given page 112, and
those just stated, and as will appear from a
number of other evidences, may be considered
as unity.

5. Of all gaseous substances, hydrogene is
most distinctly characterized as an element; and
in its relations it is opposed to oxygene.

Its extreme lightness, and the small quanti-
ties in which it enters into combination, render
it unhkely that it should be resolved into other
forms of ponderable matter, by any instruments
or processes at present within our power. Some
extraordinary phaenomena which have been
explained in the idea of its being a compound,
and which will be referred to towards the endk

[ 255 ]

of this volume, are more satisractorlly accounted
for on the idea of its being simple, or at least
a form of elementary matter.

Hydrogene gas is employed for filling
balloons, and its low specific gravity renders
it well fitted for aerostatic purposes. It
is an important principle in animal and
vegetable bodies ; and exists in larger or
smaller quantities in all organized compounds.
It is the body which gives the power of
burning with flame to all the substances used
for the oeconomical production of heat and
light.

III. Of Azote, or nitrogene Gas.

1. Azote was discovered by Dr. Rutherford
in 1772. It may be procured by extractino-
oxygene from common air, in the manner de-
scribed page 231. It is formed directly by
dissolving animal matters, such as glue or mus-
cular fibre, in diluted aquafortis, or fuming
nitrous acid mixed with ten or twelve times its
weight of water. It may be collected over
water.

Azote extinguishes flame. It is very slightly
absorbable by water ; that fluid, according to
Dr. Henry's experiments, takes up only
part of its volume. Its specific gravity, as was
mentioned in page 113, is to that of hydrogene

[ 256 ]

as 13 to 1. 100 cubical inches of it, at mean
temperature and pressure, weigh between 29
and 30 grains. According to Biot and Arrago,
its refractive power is 58976.

Its capacity for heat, according to Dr. Craw-
ford, is .7936.

2. There are several compounds containing
azote and oxygene in dijBPerent proportions;
three of which have been already referred to,
page 113. Their nature is more easily demon-
strated by analysis than synthesis ; though the
most important of them, nitrous acid in its union
with water, may be made by the direct combi-
nation of azote and oxygene with that fluid.

Dr. Priestley ascertained that acid matter
was formed by passing electrical sparks through
a mixture of azote and oxygene over water, and
Mr, Cavendish by a series of beautiful experi-
ments, proved that the two gasses combined with
the water and formed the same acid as that pro-
cured from nitre by oil of vitriol. The other com-^
pounds of azote and oxygene are alway s formed
from the decomposition of this acid, or some of
its compounds ; but as nitrous acid exists in dif-
ferent states, its properties will be best under-
stood after the more simple combinations of
azote and oxygene have been describjed.

3. JVitrous oxide, the compound containing the
smallest quantity of oxygene, was discovered by

[ ]

t)r. Priestley in 1772, and named by him de*
phlogisticated nitrous air.

It is a gaseous body, which, as has been
stated^ page 106, may be produced by heating;
nitrate of ammonia; a glass retort is employed
to contain the salt ; the flame of an Argand
lamp is sufficient to produce the gas. It may
likewise be obtained durin2; the solution of
zinc in very weak nitric acid, but in this case it
is not pure.

Nitrous oxide may be preserved over water ;
but it is absorbed by this fluid, which takes up,
-/o of its volume nearly, and for accurate ex-
periments, it should be collected in the mer-
curial apparatus.

Its degree of purity may be learnt from the
quantity absorbed by water.

Nitrous oxide exhibits the following proper-
ties. A taper, plunged into it, burns with
<rreat brilliancy, and the flame gradually be-
comes surrounded with a blueish halo. Phos-
phorus may be melted and sublimed in it with-
out inflaming ; but when introduced into it in
a state of vivid combustion, the brilliancy of
the flame is greatly increased. Sulphur and
most other combustible bodies, require a higher
decree of heat for their combustion in it than
they require in oxygene, or in the atmosphere.

Its specific gravity, according to my experi-

VOL. I. S

[ 2-58 ]

ments, is to tbat of hydrogene, nearly as 21 to
1. 100 cubical inches of it at mean temperature
and pressure, weigh between 48 and 49 grains.
Its taste is sweeiish, iis odour slight but
agreeable.

It is respirable, but not fitted to support
life. I ascertained in 1799, that when it was
respired, it produced effects analogous to those
produced by drinking fermented liquors, —
usually a transient intoxication, or violent exhi-
laration. Individuals that differ iti temperament
are however, as might be expected, differently
affected.

The nature of nitrous oxide is shewn by the
experiment referred to, page I06. One in vo-
lume of this gas is decomposed by one volume
of hydrogene, water is formed, and one in
volume of azote remains.

Or if well- burnt charcoal be inflamed in a
volume of it by a burning glass, 1 in volume
of it affords as much carbonic acid as half a
volume of oxygene, and when this carbonic
acid is absorbed, a volume of azote remains ;
so that it consists of 26 in weight of azote, and
15 of oxygene.

4. JYitrous gas was noticed by Dr. Hales,
but its properties as a specific elastic fluid were
first described by Dr. Priestley in 1772 ; it is
procured during the solution of various bodies,

C ^^59 ]

in nitric acid; sugar, silver, mercury, copper,
bismuth, afford it very readily. Filings of cop-
per are usually employed ; and a retort, or a
bottle having a tube, inserted into it is used ; the
acid (if the common acid of commerce) should
be diluted with 6 or 8 times its weight of water :
the production of the gas may be assisted by a
gentle heat.

It may be collected over water, which absorbs
only about of its volume ; but for accurate
purposes mercury should be employed.

The degree of purity of nitrous gas may be
known by agitating it in contact with sin aqueous
solution of green sulphate of iron. Nitrous gas
is quickly absorbed by this substance.

When a jar of nitrous gas is opened in the
atmosphere, red fumes appear. When an in-
flamed taper is plunged into it, the light is
instantly extinguished.

Inflamed sulphur is extinguished by it; but
inflamed phosphorus burns in it with great
brilliancy. It cannot be made to detonate when
mixed with hydrogene, by the electric spark.

Its specific gravity is to that of hydrogene.
as 14 to 1. 100 cubical inches of it weigh about
32 grains.

Whether it is respirable, or has taste or
smell, cannot be ascertained, as it instantly

[ 260 ]

unites vviili the oxygene in air, producing red
fumes, which are nitrous acid gas.

The composition of nitrous gas has. been
already referred to, page 107*

It is decomposable by several of the metals
when they are heated in it^ such as arsenic,
zinc, potassium in excess ; it oxidates them,
and aHbrds iialf its vohjme of azote. In an ex-
periment in which I decomposed a small quan-
tity by igiiiimg charcoal in it by a burning
glass, I found that it afforded about half a
volume of carbonic acid,* and half a volume of
azote ; so that it consists of 26 of azote to 30
of oxygene.

Whe;n it is exposed to certain bodies, such
as the salts called sulphites, solution of tin in
muriatic acid, or solutions of alkaline sulphurets,
it is converted into nitrous oxide ; I have found
that in accurate experiments of this kind, two
in volume of nitrous gas become one in volume
of nitrous oxide ; a circumstance harmonizing
precisely with their relative proportions of
oxygene and nitrogene.

5. It has been mentioned that the red fumes
produced by the action of oxygene and nitrous
gas, are owing to the production oi nitrous acid
gas.

It i^j not easy to ascertain the exact nature of

* See page 105»

C S61 ]

this change, as the substance formed acts both
upon mercury and upon water ; and over water
very different proportions of the gasses may be
made to condense each other. When large
quantities of nitrous gas are added to small
quantities of oxygene, in vessels of large dia-
meter, from two to three in volume of nitrous
gas, disappear for one of oxygene. When large
quantities of oxygene are added to small quanti-
ties of nitrous gas in narrow tubes, the absorption
is from I to 1.5 of oxygene in volume, and 2
of nitrous gas. From a series of experiments
on the decomposition of nitre, and others on
the mixture of nitrous gas and oxygene, exe-
cuted with great care in exhausted vessels fur-
nished with glass stop-cocks, I am incbned to
believe that the acid obtained over water by the
condensation of mixtures of nitrous gas and
oxygene is never fully saturated with oxygene,
and that the pale fluid called nitric acid consists
of water united to two in volume of nitrous
gas, and one and a half of oxygene ; and this
acid, according to its different degrees of diUi*
tion, may be made to absorb different quantities
of nitrous gas, when it becomes yellow, orange,
blue, or biueish green ; and in this last state it
it saturated with nitrous gas.

When two of nitrous gas, and one of oxy-
gene freed from moisture, are mixed together in

[ 262 ]

% vessel previously exhausted of air, they be-
come condensed to about 3^ of their volume, and
form a deep orange coloured elastic fluid, which
may be called nitrous acid gas.

This substance has the following properties :
a taper burns in it with considerable brilliancy.
Sulphur inflamed, does not burn in it ; but the
combustion of phosphorus continues with great
vividness.

Tin, copper, and mercury, act upon it slowly;
iron ignited to whiteness is rapidly cooled in it.

Charcoal inflamed, continues to burn in it
with a dull red light.

When a portion of water is exposed to it,
there is a rapid absorption, and the water gains
a tint of green.

Its smell is very disagreeable, its taste sour ;
when applied to animal substances, it renders
them yellow ; it reddens litmus paper*

Calculating from the condensation, the spe-
cific gravity of nitrous acid gas is to that of
hydrogene as about S8 to 1: and 100 cubical
inches of it weigh 65.3 grains, at mean tempe-
rature and pressure.

6. I have attempted to procure a permanent
elastic fluid, consisting of two parts in volume
of nitrous gas, and I.5 oxygene, by mixing
oxygene in excess with nitrous gas ; but the
condensation was always such as to indicate the
formation of nitrous acid gas, and the colour

[ 263 ]

was deep orange; so that the existence oFnitnc
acid as^ pure &oi/j" consisting of 1.5 of oxygene
and 9, of nitrous gas is problematical ; the
gaseous combination of nitrous gas and oxvgene
probably always contains 2 of nitrous gas, and
1 of oxygene ; and some basis seems necessary
for the union of two of nitrous gas, and I.5 of
oxygene ; such as water, alkalies, or oxides.

M. Gay Lussac supposes that there is a
compound of three of nitrous gas,* and one of
oxygene, capable of combining with water and
alkalies without decomposition. I have tried
many experiments on this subject, but have
never been able to make a strong coloured aqua-
fortis containing more than 2 of nitrous gas to 1
of oxygene in volume ; when nitrous acid gas
is passed into alkaline solutions, a portion of
nitrous gas is always evolved ; and when onp
in volume of oxygene is added to two of
nitrous gas, and dry azote introduced to mark
the condensation, no change takes place on
the mixture of the gas with fresh portions of
dry nitrous gas.

Aquafortis or nitric add. is piocured for

* It is stated that this combination can only be made over
a large surface of water, which shews either that the air in
the water is concerned in the condensation, or that the water
itself absorbs nitrous gas ; the size of the vessel can have no
influence on the compound formed, and it is supposed by
M. Gay Lussac, readily absorbable by water, Mem. D'Arcueil ,
T. II, page 2il,

[ 264 ]

the purposes of chemistry by the distillatioa
of nitre and oil of vitriol ; about 2 parts of
nitie should be used to 1 part of oil of vitriol,
and the retort heated in a sand bath connecteci
with a receiver kept cool by moistened cloths.
The acid thus obtained is usually coloured,
but becomes pale by exposure to air. If the
nitre is dry, its specific gravity is from 1,520
to 1 55 This substance acts with great violence
on all the metals anciently known^ except orold
and platina, and causes volatile oils to inflame.
When it is passed through a porcelain tube
heated to redness, oxygene is given off from it,
and nitrous acid gas ; and the same effect is
produced upon the residual acid, as if it had been
mixed with water ; so that it is proved by this
experiment to be composed of nitrous acid gas,
oxygene, and water; and 4 in volume of nitrous
gas, and 2 of oxygene gas condensed in water, I
find, absorb 1 in volume of oxygene to become
nitric acid.

7. To enter upon a description of all the ex-
periments that have been made to ascertain the
quantities of water in acids of differentstrengths,
would be unfitted to the nature of an elemen-
tary treatise.

From my own experiments compared with
those of Kirwan, Wenzel, and Berthollet, I am
inclined to believe that the strongest acids con-
^ain from 14 to 15 per cent, of water, and accorc^^

[265 ]

insr fo tKe principles of the French nomencla!-
ture, they ought to be called hydro-nitric acids.

Aqoafortis, or hydro nitric acid, when its spe-
cific gravity is below I.4, strengthens by being
boiled; when stronger than I.45, it becomes
weaker by boiling. According to Mr. Dalton,
the acid of distills unaltered at 24H° Fah-
renheit. It is probable that the acid of 1. 55
consists of one proportion of water and one of
acid, and ihat which rises unaltered at 24S°
of one proportion of acid and two of water.

if nitrous gas be considered as represented
by 56, that is, by one proportion of azote, and
two of oxygene, 26 and 30, then nitrous acid
gas will be represented by 86, or one of azote,
S6, and four of oxygene, 60 ; and 101 will be
the number for the acid contained in the pale
acids, and in the salts called nitrates, and it will
consist of one of azote and five of oxygsne.

And the strongest acid will contain 1 7
-water and 10 1 acid, and the acid of I.42 34
water and iOl acid.

Hydro-nitric acid is of great use in many of
the common arts. It is employed in medicine,
for dissolving metals, for etching, for making
compounds used in dyeing, and it is one of the
constituent parts of nitre, a substance essential
in the munuiacture of gun-powder.

6. Azote and chlorine have no cl]emical action

[ 266 ]

on each other in any circumstances to which
they have been hitherto exposed.

I caused the Voltaic flame from 1000 double
plates to pass through a mixture of them in a
close vessel for some minutes ; but the azote
underwent no change, nor was any combination
effected.

S. Azote and hydrogene exist in combination
in ammonia or the volatile alkali. It is not
easy to produce their union, yet when azote is
exposed to moist substances giving off hydro-
gene, a little ammonia is found after some time
in the water ; — for instance, when azote is
placed in contact with moist iron filings above
mercury. Priestley first procured ammonia in
its pure form ; and his experiments, and those
of Scheele, repeated and illustrated in an ela-
borate manner by Berthollet, led to the
knowledge of its elements ; indeed the last
chemist must be considered as the true disco-
verer of the composition of ammonia.

To procure ammonia, equal parts of well
burnt dry lime and dr^ salammoniac or muriate
of ammonia, are heated in a retort of glass,
the beak of which is plunged under dry mer-
cury. Gaseous matter comes over, which when
the common air of the retort has been all ex-
pelled, must be collected in inverted jars filled
with mercury.

.[ ]

Ammonia at commoti temperatures is a per-
manent gas; according to Guyton de Morveau
it becomes a liquid at about 70 below 0 of Fah-
renheit's scale : but his experiments were made
in glass balloons, and the conclusions drawn
from the appearance of fluid ; so that the evi-
dence, though strong, cannot be regarded as
perfectly satisfactory, as ammonia contains va-
pour which must be condensed to a great extent
by so intense a cold.

The specific gravity of ammonia is to that of
hydrogene, nearly as 8 to 1. 100 cubical inches
of it weigh at mean temperature and pressure
about 18 grains.

When an inflamed taper is plunged into a
jar of ammonia the light is extinguished ; but
a slight inflammation of the gas occurs where
it is in contact with air.

Its taste is extremely acrid : it cannot in-
deed be safely applied to the organs of taste or
smell except when mixed with much common
air. It is the principle which gives pungency
to the common concrete volatile alkali.

It instantly reddens paper tinged with tur-
meric, and gives a green colour to most vege-
table blues and reds; and this property, and
its other properties, characterise it as an alka-
line body.

It is rapidly absorbed by water. At the tem-
* Annales de Chimie XXIX. page 292.

[ 268 ]

perature of 50® under a pressure equal to
inches, water, I find, absorbs about 670 times its
volume of gaSj and becomes of specific gravity,
.S75.

Tbe following table containing approxima»
tions to the quantities of ammoniacal pras in
aqueous solutions of diiferent specific gravities,
was constructed after experiments made with
great care for the purpose^

100 1 arts
of specific
gravity.

Of Ammo-
nia.

*8750

3-2.5

8875

29-25

9000

26.00.

; §054*

525.37

S16V)

r:

22.07

5/255

19.54

17 52

9385

15M

94-35

14.53

947 &

13 46

9513

12.40

904.5

11.56

9573

10.82

9m

10.17

S619

9-6o

5-50

The censtitution of ammonia may be easiljr
demonstrated by analytical experiments, it is
decomposed by electrical sparks, or by being
passed through a tube heated to redness; its

* The three results marked by the asterisk, were gained bj
expeiimentsj the other numbers by calculationit

[ m ]

"volume is increased, and it becomes bydrogene
and azote.

M. Berthoilet jun. conceives that its volume
is doubled when it is decomposed over mercury
by eie<:trical sparks. In Dr. Henry's experi-
ments and those that I have made, the expan-
sion is a little less ; but this is probably owing
to the unavoidable imperfection of the process.
I once thought that a small quantity of water
was formed in the operation, but verv delicate
experiments have conviuced me that this is not
the case. I decomposed a quantity of ammonia
by electric sparks in a close vessel, in which its
elements could not expand, and yet no moisture
was deposited.

In the most accurate experiments in which,
the hydrogene lias been separated from the
azote by successive detonations with small
quantities ofoxygene; the volumes have been
S of hydrogene to I of nitrogene, so that am-
monia consists in weight of 3 of hydrogene and
13 of nitrogene, and supposing the number re-
presenting hydrogene unity, the same number
is gained to represent azote as from the pro-
portions of the elements in its compounds with
oxygene ; and ammonia consists of one propor-
tion of azote and six of hydrogene, and is
represented by 32. That all these conclusions
are correct is shewn by the decomposition of the
compound made from nitric acid and ammonia

[ 210 ]

When this salt, which is called nitrate of
ammonia, is exposed to a heat gradually raised,
it is decomposed into water and nitrous oxide ;
and this could not happen unless it were con-
stituted by definite proportions, which must be
101 of acid and 32 of alkaline matter; for 6
of hydrogene require 45 of oxygene to pro-
duce water, and 52 of azote i.e. 26 in the acid,
and 26 in the alkali require 30 of oxygene to
produce nitrous oxide.

Ammonia is employed in medicine, and its
compounds are used in processes of dyeing, and
in some of the metallurgical arts.

8. Azote has not as yet been resolved into
any other forms of matter. I volatilized the
highly combustible metal potassium in azote
over mercury, and passed the Voltaic flame of
2000 double plates through the vapour ; but
the azote underwent no change^ I have made
many other attempts to decompose it, but they
have been unsuccessful.

The strongest arguments for the compound
nature of azote are derived from its slight ten-
dency to combination ; and from its being found
abundantly in the organs of animals which feed
on substances that do not contain it.

Its uses in the oeconomy of the globe are
little understood ; this likewise is favourable to
the idea that its real chemical nature is as yet

C 271 ]

unknown, and that it is not actually an unde-
composable substance.

It would appear that azote and oxygene
combine slowly under certain circumstances
in natural operations, when lime or alkaline
substances are present ; thus nitrous salts ,are
produced in nitre beds in warm climates, and
the process is assisted by, or the combination
formed during the fermentation of animal and
vegetable substances.

Ill, Of Sulphur.

1. Sulphur is a well known substance, found
native in many parts of the world, and it may
be procured by the distillation of the mineral,
called pyrites.

It is brittle, moderately hard, and of a yellow-
ish colour, and has a peculiar taste and smell.
It is a nonconductor of electricity. Its specific
gravity is 1990. It is often found in regular
solid forms, usually octohedral, when it is more
or less transparent. Its power of refracting light
according to Dr. Wollaston, is to that of water
as .204 to .1336: its capacity for heat is
stated to be as 1.9 to 1, It fuses at about 220°
Fahrenheit, and volatizes slowly even before it
fuses ; at the temperature of 560° it becomes an
elastic fluid, and in this state inflames if in con-
r» tact with air, and burns with a pale blue flame.

2. If sulphur be heated above 300° Fahrenheit,

t J

It graduallly becomes thick and viscid, when if
it be poured into a bason of water, it will be
found of a red colour, and ductile like wax. In
this state it is used for receiving impressions of
seals or medals. Its specific gravity is increased
according to Dr. Thomson, to 2325 during this
process ; from which it seems probable that its
parts undergo a new arrangement, and approach
nearer, than in its common crystalline form. It
has been supposed that the change depends upon
its combining with oxygene ; but in some expe-
riments made expressly to ascertain this pointy
it was not found that any oxygene was absorbed
when sulphur was long kept heated in ecntact
with it in close vessels, and 1 have observed
after Dr. Irvine, jun. that the change of colour
takes place independent of the presence of air.

3. The only well known compound consisting
of sulphur and oxygene alone, is a gaseous sub^
stance, called in the modern nomenclature^ *u/-
phureous acid gas. It may be procured by heating
sulphur in oxygene gas ; the experiment may
be performed in a glass retort, and the sulphur
inflamed by a spirit lamp ; it burns with a beau-
tiful violet flame, and if the oxygene gas has
been carefully freed from water, sulphureous
acid gas will be the product. It may be formed
likewise by heating mercury or copper filings^
in oil of vitriol, and collected over mercury.

Sulphureous acid gas has a very disagreeable

[ 273 ]

<!mell. it is the smell of taurning sulphur* It
reddens vegetable blues, and gradually destroys
most of them. It whitens many animal and ve-
getable substances, silk atld straw for instance ,
and hence the vapours of burning sulphur are
iemployed in bleaching.

Its specific gravity is to that of hydrogene
as 30 to I., and 100 cubical inches ofitatmeaii
temperature and pressure, weigh about §B
grains.

It is absorbed by water ; this fluid takes up
about 30 times its bulk, gains a nauseous sub-
acid taste, and according to Dr. Thomson, be-
comes of specific gravity 1.05 13.

That sulphureous acid gas consists of sulphur
and oxygene, iS evident from the phsenomena
of its production by combustion.

In several experiments in which I burnt sul-
phur, procured from iron pyrites out of the
contact of air or moisture, in dry oxygene gas
over mercury, I found that the volume of the
Oxygene was very little altered ; the condensa^
tion was never more than ^V? z*nd seldom so
thuch as and I am inclined to attribute the
loss to the formation of a little oxide of sul-
phur, or to a little hydrogene loosely combined
with the sulphur, so that there is every reason
to believe that sulphureous acid is constituted
by sulphur dissolved in a volume of oxygene.

VOL. I. T

[ 274 J

Tills conclusion is confirmed by some ex-
periments on the action of cinnabar, wliich
consists of mercury united to sulphur, and sul-
phur itself, on metallic oxides.

Two ecjual quantities of red oxide of mercury
each weighing 10 grains, were heated one
alone, the other mixed with sulphur. They
afforded nearly equal volumes of gas. One,
which equalled 2 cubical inches and — •, was
oxygene, the other, which equalled 2 cubical
inches and was pure sulphureous acid gas.
Similar experiments were made, cinnabar being
ubstituted for sulphur, with like results.

If the specific gravities of sulphureous acid
gas and oxygene be compared, and the last
subtracted from the first, it will appear that
sulphureous acid consists nearly of equal parts
of oxygene and sulphur by weight.

4 If a solution of sulphureous acid gas in water
be exposed to .the air, it looses its peculiar
flavour, and becomes strongly sour ; and ex-
periments on the action of the solution on air,
shew that oxygene is absorbed.

Sulphureous acid gas is easily driven off from
water in the recent solution, but after it has
been changed by exposure to air, water only
rises when it is heated ; and if the evaporation,
is carried on till the temperature is 546° the resi-
duum is found to be the same substance as oil

[ 275 ]

of vitriol; nothing but water will have been
given off; and therefore oil of vitriol contains
sulphur combined vi'ith more oxygene than in
sulphureous acid. That it likewise contains
water, is shewn by another experiment, which,
if made with accuracy, affords perfect evidence
of its nature and composition. Let a porcelain
tube be heated red, and the strongest oil of*
vitriol passed through it in vapour, a part of
it will be decompounded, the gaseous products
wiJl be two parts of sulphureous acid gas, and
one part of oxygene gas ; and the fluid product
will be a weaker acid, such as would be pro-
duced by diluting the acid which is the subject
of experiment.

The compounds made by adding oil of vitriol
to the alkaline earths, free, as far as our know-
ledge extends, from water, give off moisture
when they are heated to redness, and if the
quantity of water in the strongest oil of vitriol,
be estimated from experiments of this kind, it
may be concluded that it contains about 19 per
cent, of water ; and its composition may be thus
expressed, SO of sulphur, 45 of oxygene, and 17
of water.

In the common process of manufacture, oil of
vitriol is made by burning sulphur mixed with
about -i- of its weight of nitre in pans of iron op
lead communicatiBg with a chamber of lead,

T2

[ 276 J

the bottom of which is covered to the depth of
several inches with water. The true theory of
this process is not given in any chemical book.

The sulphur by burning, forms sulphureous
acid gas, and the acid in the nitre is decom-
posed, giving off nitrous gas ; this coming in con-
tact with the oxj^gene of the atmosphere, pro-
duces nitrous acid gas, which has no action upon
sulphureous acid, to convert it to sulphuric acid,
unless water be present, and if this substance be"
only in a certain proportion, the water, the ni-
trous acid gas, and the sulphureous acid gas
combine, and form a white crystalline solid. By
the large quantity of water usually employed,
this compound is instantly decomposed, oil of
vitriol formed, and nitrous gas given off, which
in the air J again becomes nitrous acid gas, and
the process continues according to the same prin-
ciple of combination and decomposition, till the
water at the bottom of the chamber is become
strongly acid. It is easy to prove the truth of
these reasonings ; let dry sulphureous acid gas,
and nitrous acid gas be mixed together, by suf- ,
fering the sulphureous gas to pass into a glass ,
globe partially exhausted, and containing nitrous
acid gas. There will be no action between the
gases. But if a drop of water be introduced,
there will be an immediate condensation, and
a beautiful white crystalline solid will line the

. t 277 ]

iftterior of the vessel. Whereas if the globe con-
tain plenty of water, nitrous gas will be given off
with great violence, and the water will be found
to be a solution of oil of vitriol.

In the solid crystalline compound, it is evi-
dent, from the products of its decomposition by
water, there must be four volumes of sulphureous
acid gas, and three of nitrous acid gas, probably
in two or three proportions with a single propor-
tion of water ; for nitrous acid gas contains -f of
its volume of loosely combined oxygene, and sul-
phureous acid gas requires half its volume of
oxygene to become, when condensed in water,
solution of oil of vitriol.

Mr. Dalton, who has adopted M. M. Clement's
and Desormes' idea of nitrous acid gas being, de-
composable by sulphureous acid gas, which is not
correct, supposes that there is a solid sulphuric
acid, the oxygene in which is to that in sulphu-
reous acid, as 3 to 2; but the body which he
supposes to be sulphuric acid is the crystalline
substance, the nature of which is demonstrated
above : and no substance to which the name of
pure sulphuric acid ought to be given, i. e. a sub-
stance consisting of 30 of sulphur and 4.5 of oxy-
gene, has yet been discovered in an insulated
state.

The term sulphuric acid, is improperly ap-
plied to the strongest oil of vitriol; this sub-
stance, according to the principles of the French

[ 278 ]

nomenclature, ought to be called hydrosiilpkiiric
acid.

The oil of vitriol of commerce, which is of
specific gravity 1.85, rises in vapour at about
550° Fahrenheit, and distils unaltered ; whereas
weaker acids, by being boiled, lose water, and
are brought to this state of concentration. There
is a diluted acid of specific gravity 1.78, which;
congeals at any temperature below 46° Fahren-
heit. It is very curious, as Mr. Dalton has
stated, that this acid contains exactly twice as
much water as the acid of 1.85. It is composed,
according to my experiments, of 30 of sulphur,
45 of oxygene, and 34 of water.

Pure oil of vitriol is a corrosive substance.
It acts with great energy upon animal and ve-
getable matter. It rapidly attracts moisture
fro^ the air, and produces much heat whea
mixed with \vater. It reddens vegetable blues j
and acts with great violence upon alkaline sub-
stances, and upon certain earths and metallic
oxides ; and neutral salts are produced by the
union of its sulphur and oxygene with these
bodies.

The number representing sulphur, as learnt
from the constitution of sulphureous acid gas,
is nearly SOj and as this gas contains two pro-
portions of oxygene twice 15, it would seem
probable that an oxide of sulphur may exist,
consisting of 30 of sulphur, and 15 of oxygene.

[ 279 ]

I have examined some highly coloured spe-
cimens of Sicilian sulphur, which seemed to
contain a little oxygene, and as has been just
stated,, it' is possible that a little oxygene may
be condensed in the combustion of sulphur in
the residuum ; but as yet no body is known
that can with propriety be called oxide of sul-
phut\

5. Sulphur and chlorine are possessed of a
chemical attraction for each other. The first
combination of them was made by Dr. Thom-
son in 1804, by passing chlorine over flowers
of sulphur. It may be made more expeditiously
by heating sulphur in a retort filled with chlo-
rine. The sulphur and the chlorine unite and
form a fluid substance, which is volatile below
200° Fahrenheit, and distills into the cold part
of the retort. This substance seen by reflected
light, appears of a red colour, but is yellowish
green, when seen by transmiited light. It
smokes when exposed to air, and has an odour
somewhat resembling that of sea weed, but
much stronger ; it affects the eyes like the smoke
of peat. Its specific gravity, according to Dr.
Thomson, is 1.6.

It does not redden perfectly dry paper
tinged with litmus ; when it is agitated in
contact with water, the water becomes cloudy

[ 280 ]

from the appearance of sulphur, and strongly-
acid, and it is found to contain oil of vitriol.

According to my experiments, 10 grains of
pure sulphur absorb nearly 30 cubical inches
of chlorine; so that the compound contains
about 30 of sulphur to 68.4 of chlorine ; 30 of
sulphur to 67 of chlorine, would give one pro-
portion of sulphur to two of chlorine ; which,
there is every reason to believe, must be the
just estimation ; for my experiments were made
in retorts furnished with metallic stop-cocks,
by which a little chlorine must have beer?,
absorbed.

The compound formed in the manner above
described cannot be made to unite to more
chlorine ; but J find it dissolves a considerable
portion of sulphur by heat, and becomes of a
tawney yellow colour.

Dr. Thomson called this substance sulphu-
retted muriatic acid, but there is no proof that
it contains muriatic acid. According to an
idea which I ventured to propose in the Phi-
losophical Transactions for 1811, that of calling
the compounds of chlorine by the rjameof their
bases, with a termination in " ane" its name
>vould be sulphurane.

6, Sulphur and hydrogene combine. Their
unioji inay be effected by causing sulphur to

[ SSI ]

sublime in dry liydrogene in a retort. There is
no change of voluirxe : but only a part of the
hydrogene can be combined with sulphur in
this mode of operating.

The gaseous compound of sulphur and hy-
drogene was discovered by Scheeie, in 177 7.
It is usually made by the action of diluted
sulphuric acid upon a mixture of three parts of
iron filings, and two parts of sulphur that have
been ignited together ; for the purposes of ac-
curate experiments, it should be collected over
mercury.

Sulphuretted hjdrogene inflames when a
lighted taper is brought in contact with it, ex-
posed to the air : it burns with, a pale blue
flame, depositing sulphur. Its smell is ex-
tremely fetid, resembling that of rotten eggs.
Its taste is sour. It reddens vegetable blues.
It is absorbable by water ; that fluid takes
up more than an equal volume of the gas. Its
specific gravity, according to M. M. Gay Lussac
and Thenard, is to that of air as 1,1912 to I.
Frorn my experiments it would appear to be
a little less ; hut I am inclined to adopt the
results of the French chemists rather th^n my
own, as their gas was weighed in larger quan-
tity, and dried. Its weight to that of hydrogene
may be considered as 16 to 1, and IQO cubical

E 283 ]

inches of it, at mean temperature and pressure,
weigh between 36 and 37 grains.

The composition of sulphuretted hydrogene
is demonstrated by the change produced in it
by electricity ; if platina wires be ignited in
it by the voltaic apparatus, it is rapidly de-
composed. Sulphur is deposited, and an
equal volume of hydrogene remains; the
same change is effected more slowly by elec-
trical sparks.

The proportion of its elements are shewn to
be the same, both by the analytical and synthe-
tical experiments. They must be 15 of sulphur -
to 1 of hydrogene ; and the results give as
nearly as possible the same number represent-
ing sulphur, as its compounds with oxygene
and chlorine : and sulphuretted hydrogene may
be considered as consisting of two proportions
of hydrogene 2, and 1 of sulphur, 30.

This body combines with an equal volume
of ammonia ; and unites to alkalies and oxides,
so that it has all the characters of an acid.

7. There is another compound of hydrogene
and sulphur, the proportions of the elements
of which have not yet been accurately ascer-
tained ; but it probably will be found to con-,
tain at least one proportion more of sulphur.
Xt may be formed by passing sulphur over

[ 283 ]

charcoal ignited in a porcelain tube, the expe-
riment must be made with the excliision of air.
It is a fluid body, and was discovered by
Lampadius, in 1796, and called by him ak0h'Oi
€>f sulphur. Its colour is greenish yellow.
Its taste pungent, its smell peculiar, its specific
gravity is 1.3. It is very volatile. It does not
mix with water. It burns with the same FaGility
as spirits of wine. It dissolves sulphur with
great facility by the assistance of heat ; andif
when the saturated solution of sulphur in this
substance is exposed to air, as the alcohol c£
sulphur evaporates, chrystals of sulphur are de-
posited. When it is exposed to platinum ignited
by the agency of Voltaic electricity, it gives off
sulphuretted hydrogene. This, and the phas-
tiomena of its combustion, demonstrate its
nature, for when it burns in contact with oxy^-
gen€, the products are sulphureous acid and
oil of vitriol.

When quicksilver is heated in the vapour of
alcohol of sulphur, a compound of sulphur and
quicksilver is formed, and sulphuretted hydro-
gene disengaged.

8. Sulphur has no chemical attraction foP
azote, at least no compound of these bodies has
as yet been formed.

9. Sulphur has been placed amongst the urs-
tlecompounded bodies, because as yet nothiu2;

[ m ]

eertain is known respecting its elements. Wheii
Sicilian sulphur was fused and exposed to the
action of platina points intensely ignited by
Voltaic electricity, excited by 1000 double
plates, permanent gas was given off from it,
which proved to be sulphureted hydrogene
a small quantity of sulphuretted hydrogene is
given off likewise during the action of copper
tilings upon sulphur ; and the mode of the for-
mation of alcohol of sulphur, proves that sul-
phur or charcoal, or both, contain hydrogene.
It may however be questioned whether hydro*-
gene is essential to the constitution of sulphur.
Sulphur may possibly contain in its common
forms a little moisture, or a little of a solid
compound of hydrogene and sulphur ; and
till the gas can be separated from it in definite
proportion, and be proved to be combined with
some other matter, no accurate conclusions can
be formed upon the subject.

Sulphur is employed in medicine, particularly
as an external application in cutaneons com-
plaints. Its use in bleaching has been already
referred to. Its most important application is in
oil of vitriol, and the compounds formed from
it, which are used in various processes of dyeing
and calico-printing.

[ 2S5 ]

IV. Of Phosphorus.

1. Phosphorus was discovered by Brandt iri
I669. It may be made by the following
process.

A hundred parts of burnt bones in powderj
are to be mixed with 40 parts of oil of vitriol,
and they are to be suffered to remain in con-
tact for a couple of days, the mixture being
frequently stirred. The whole is then to be
poured upon a filtre of cloth, and the liquor
that passes through is to be added to a nitrous
solution of lead ; a white powder will be formed ; .
this must be mixed with about -f of its weight
of charcoal powder, and exposed to a strong
red heat in a porcelain retort, the beak of which
is plunged in Water; much gaseous matter will
come overj some of which will inflame sponta-
neously, and at length a substance will drop
out of the neck of the retort, and congeal
under the water, which is phosphorus. It may
be purified by melting it in water, and passing
it under water through sharaois leather.

2. Phosphorus is semi-transparent, and of a
yellowish colour. It is as soft as and more ductile
than wax. It is insoluble in water. Its specific
gravity is about 1.7 7- It melts at the tempera-
ture of 90°, and boils at about 550°.

When phosphorus is exposed £0 air at com-

[ ]

mon temperaturesjit emits a white smoke, which
appears luminous in the dark. This depends
upon its combining with oxygene, and forming
an acid which unites to the aqueous vapour in
the atmosphere, and they fall down in the fluid
form. Phosphorus, I find, does not smoke in
air perfectly dry ; and in this case the acid ad-
heres to it, and in a short time prevents it from
being luminous.

When phosphorus is heated to about 148°,
it takes fire, and burns with intense brilliancy,
throwing off dense white smoke, which is a
strong solid acid that soon becomes liquid by
attracting moisture from the air ; and a red
substance usually remains.

3. The manner in which phosphorus acts
upon air, as has been shewn, page 231, proves
that it is capable of combining with oxygene ;
and there is every reason to believe in at least
' three proportions.

When phosphorus is inflamed in oxygene
gas over mercury, and the white substance pro-
duced strongly heated, the oxygene being in
excess, for every grain of phosphorus burnt
four cubical inches and a half of oxygene gas
are absorbed. The substance so procured is called
phosphoric acid. It becomes fluid at a red keat ;
it is not volatile even at a white heat. It has no
smell; its^tasteis intensely, but not disagreeably

[ 287 ]

iscid. It dissolves in water, producing great
heat; and its saturated solution is of the con-
sistence of syrup. It acts upon, and corrodes
glass, and unites to alkalies and oxides.

4. When phosphorus is heated in highly
rarefied air, three products are formed from it ;
one is phosphoric acid ; one is easily volatile,
and appearing as a white powder ; and the
other is a red solid, comparatively fixed, and
requiring a heat above that of boiling water
for its fusion. The volaiile substance is soluble
in water; and gives it acid properties. It con-
tains less oxygene than phosphoric acid ; for it
burns and becomes fixed when heated strongly
in the air. Its taste is sour, with a peculiar pun-
gency, and it emits a smell not unlike that of
garlic. It is mixed with phosphorus, but is prin-
cipally the substance which, according to the
French nomenclature, should be called phos"
phorous acid, and which in chemical works, is
inaccurately described as a fluid body. The
red substance requires less oxygene than
phosphorus to convert it into phosphoric
acid, and must be considered as an oxide, of
phosphorus.

I have never been able to procure phospho-
rous acid by combustion free from admixture or
combination with other substances. In the com-
mon mode in which it is said to be obtained,

[ ^88 1

tiamely by exposing phosphorus to free dir ;
there is always a large quantity of phosphoric
aeid formed*

A pure solid kydro-phosphorous acid, that is a
Combination of it with water, may, I find, be
produced by the following process.

Phosphorus is sublimed through corrosive
Sublimate in powder in a glass tube ; a limpid
fluid comes over, which must be mixed with
water, and thei solution heated till it is of the
thickness of syrup. It is a combination of
water and pure phosphorous aeid. It reddens
vegetable blues, and combines with alkalies,
and has all the characters of a strona: acid. It
forms a white crystalline solid on cooling.

It becomes Solution of phosphoric acid slowly
when exposed to air, absorbing oxygene. When
it is gently heated, it takes fire and burns with
great brilliancy, emitting globules of gas that
inflatne in contact with air ; a red oxide of
phosphorus is deposited in the bottom of the
tessel, and solid phosphoric aeid is formed.

The substance produced by passing phos-
phorus through corrosive sublimate, as will be
immediately shewn, is a compound of phos°
phoruS and chlorine ; and when it acts upon
water, hydrogene is afforded to the chlorine,
and oxygene to the phosphorus; there are no*
products, but muriatic acid gas and phosphorous

htid, and the qoantity of hydrogene in the
miiriaUcacid gas formed, being known, the quan*
tity of oxygene in the phosphorous acid is
likewise known. By two experiments made
with great care, in which the quantity of chlo-
rine in the liquor from the phosphorus and
Corrosive sublimate, was estimated by its com-
bination with silver, I ascertained that ten
grains of phosphorus required for their con-
version into phosphorous acid, such as ex:ists
in the hydrat jost described, 7.7 grains of
oxygene ; and it is evident from this result,
compared with that on the combustion of
phosphorus, in which phosphoric acid is formed,
that the quantity of phosphorus being the
same, it requires twice as much oxygene to
become phosphoric acid, as it requires to form
phosphorous acid ; and from these data,
the number representing phosphorus, must
be regarded as about 20, and phosphoro .?s
acid will consist of ^0 phosphorus, and 1 5
oxygene, or S5; and phosphoric acid of ^0
phospi^orus and 30 oxygene, or 50.

That the hydro-phosphorous acid is a com-
pound of phosphorus, oxygene, and water, is
shewn by heating it in contact with ammonia
over mercury ; the ammonia unites to the pure
acid, and water is expelled, 1 find by experi-
ments on the quantity of water it affords, that

VOL. I. U

[ 290 ]

it consists of four proportions of phosphorous
^cid, and two of water.

I have made no experiments on tlie propor-
tion of oxygene in the red oxide. It possibly
will be found to consist oF two proportions of
phospliorus, and one of oxygene.

5. Phosphorus and chioiine combine with
great facility when brought in contact with each
other at common temperatures; and compounds
may be formed from their union, containinar
different proportions of the two elements.

Wlien chlorine is introduced into a receiver
exhausted of air, and containing phosphorus,
the phosphorus takes fire and burns with a pale
flame throwhig off sparks, and a white substance
rises and condenses on the sides of the retort.

If the chlorine be in considerable quantity, as
much as twelve cubical inches to a grain of
phosphorus, the phosphorus will entirely dis-
appear, and nothing but the white powder will
be formed ; and about 9 cubical inches of the
chlorine will be found to be absorbed ; and no
new gasecus matter will be produced.

The powder is a compound of phospho-
rus and chlorine. I first described it as a
peculiar body in 1810, and various analytical
and synthetical experiments which I have made,
prove that it is composed of about 1 of phos-
phorus and 6.8 of chlorine in weight.

[ 291 ]

Its properties are very peculiar. It is a snow
white substance. It is very volatile, and rises
in a gaseous form at a temperature much below
that of boiling water ; under pressure it may
be fused, and then it crystallizes in prisms
which are transparent.

It acts violently upon water, which it decom-
poses. Its phosphorus combines with the oxy-
gene, producing phosphoric acid, and its chlo-
rine with hydrogen e forms muriatic acid.

It produces flame when exposed to a lighted
taper ; and when passed through a glass tube
heated red, with oxygene, is decomposed; the
oxygene forms phosphoric acid with the
phosphorus, and the chlorine is disengaged.
Dry litmus paper exposed to its vapour in a
vessel exhausted of air is reddened. It com-
bines with ammonia when it is introduced into
a vessel containing it, with much heat ; and they
form together a compound insoluble in water,
indecomposable by acid or alkaline solutions,
and havincr characters analogous to an earth.

It is evident from the analysis, that it consists
of two proportions of chlorine, supposing the
number representing chlorine, 67, or of four,
supposing it 33.5, 134 to one of phosphorus
20, and the number representing it is 154' It
is analogous to an acid in many ol it& properties.
According to the princjpJes of nomenclature

[ 292 ]

which I have ventured to propose, its name will
be phosphorana.

6. I have already referred to the substance
produced by passing phosphorus through cor-
rosive sublimate. It is a fluid as clear as water ;
its specific gravity is to that of water as 1.45
to I. It may be called phosphorane. I first
obtained it in a pure form, in 1809. It ap-
pears from the circumstances already detailed,
that it consists of one proportion of phosphorus
20, and one of chlorine 67, and the number re-
presenting it is 87.* It emits acid fumes when
exposed to air, decomposing the vapour in the
air, and if made to moisten paper, it is converted
into acid in the air, without any inflammation.
It does not redden dry litmus paper plunged
into it; the vapour from it burns in the
flame of a candle ; its action upon water has
been already referred to. When it is intro-
duced into a vessel containing chlorine, it is
converted into phosphorana: if made to act
upon ammonia, phosphorus is produced, and
the same compound as that formed by phos-
phorana and ammonia.

7. When phosphorus is gently heated in
phosphorane, a part of it dissolves, and the

* 13.2 grains of it decomposed by nitrate of silver, afforded
43 grains of hornsilver, and 100 grains of silver absorb 32.i>
of chlorin« to become hornsilver.

C 293 ]

fluid, when exposed to the air gives off acid
fumes from its action upon the vapour it con-
tains, and a thin film oF phosphorus is left
behind, which usually inBames by the heat gene-
rated from the decomposition of the vapour.
The first compound of this kind was obtained by
M. M. Gay Lussac, and Thenard, by distil-
ling phosphorus and calomel together in I808,
and they imagined it to be a peculiar combination
of phosphorus, oxygene, and muriatic acid.

No experiments have been as yet made to
determine the quantity of phosphorus which
phosphorane will dissolve ; probably a defi-
nite combination may be obtained^ in which the
proportions of chlorine will correspond to the
proportions of oxygene in the oxide of phos- ^
phorus.

8, An elastic fluid, which has the peculiar
property of inflaming in contact with the atmo-
spherCj may be procured by heatipg together
slacked lime, or strong solution of potassa or
soda, and phosphorus. It is expedient to de-
prive the air contained in the vessel in which
it is generated of oxygene, by burning phos-
phorus or a taper in it ; the gas should be pre-
served over mercury ; it soon becomes adulte-
rated by exposure to water containing air.

This gas differs in properties according to
the manner in which it is made ; I have ob-

[ 294 ]

famed it from phosphorus and alkaline lixivsa,
of specific gravities varying from 4 to 7, 1 h-ing
the standard ofhydrogene: its smell is very
disagreeable : water absorbs about •—- of its vo-
lume of the gas. It detonates when brought
into contact . with chlorinej producing a brilliant
green light ; but the results of the detonation
have never been minutely examined. It ex-
plodes with a most intense white liaht in oxy-
gene gas ; the heaviest spontaneously inflam-
mable gas that I have ever made, absorbed ra-
ther less than an equal volume of oxygene.

When electrical sparks are passed through
gasses of this kind for a long time, a reddish
film which burns like phosphorus is deposited ;
usually there is lio change of volume, and the
remaining gas is hydrogene. When a gas, the
speciiic gravity of which was 6, was heated for
some time over mercury in contact with zinc
filings, there Mas an expansion of volume to
more than -§- ; a substance was formed superfi-
cially on the zinc, which had the characters of
a cofiipound of phosphorus and zinc. There
was an expansion when finely divided platina
was heated in a portion of the same gas. Pot-
assium in excess made to act upon it by a spirit
lamp produced a rapid increase of its volume ;
2 parts became rather more than The
potassium was aliected as it would have been

[ 295 ]

by a union with pliospborns, and the gas was
found to be pure hydrogene.

This substance, which was discovered by
M. Gengembre in 1783 has been called phos-
phoretted hydrogene,

9. When solid hydrat ofphosphorous acid is
heated in a retort out of the contact of air, solid
phosphoric acid is formed, and a large quantity
of elastic fluid is generated, which has very pecu-
h'ar properties ; I discovered it at the same time
as the solid hydrat of phosphorous acid, namely,
in February 18i2. This gas has a disagreeable
smell, but not nearly so fetid as that of phos- '
phoretted hydrogene : it does not explode
spontaneously, but detonates violently when
heated in contact with oxygene to about 30O
Fahrenheit. It explodes in chlorine with a whice
flame. Water absorbs -f of its volume of this
gas. In an experiment in which a small quan-
tity only was weighed, its specific gravity
appeared to be to that of hydrogene as about
12 to U

When potassium is heated in it, its volume
is doubled, and the gas produced is pure
hydrogene. When sulphur is sublimed in one
volume of it, a sul phuret of phosphorus is formed,*
and nearly 2 volumes of sulphuretted hydrogene

• See page 297.

I

[ 296 ]

produced. M^hen detonated with oxygene m
excess, three in volume of it absorb more than
five in volume of oxygene, and a little phos-
phorusis always thrown down ; when 8 of it in
volume are detonated by an electrical spark with
2 of oxygene, there is a considerable deposition
of phosphorus, and 9 of gas, which has the
odour of common phosphoretted hydrogene
lemain ; one volume of it absorbed nearly four
volumes of chlorine.

I venture to propose the name of /t/-drophaspho ^
lie gas for this elastic fluid. It appears to be
composed of 1 proportions of phosphorus and 4
of hydrogene, two volumes of hydrogene being
compressed in the space of one, and the nam-*
ber representing it is 24.

It is probable that the gas called phosphiw
reted hydrogene sometimes contains this gas,
mixed with common hydrogene, and perhaps a
peculiar elastic fluid, consisting of one propor-
tion of phosphorus, and two of hydrogene,
which has the property of spontaneous inflam-
mation. Hydrophosphoric gas I find does not
become spontaneously explosive by .mixture
with hydrogene.

There is not, perhaps, in the whole series of
chemical phsenomena a more beautiful illus->.
Ration of the theory of definite proportions^

[ 291 ]

than that offered in the decomposition ofhy-
drophosphorous acid into phosphoric acid and .
hydrophosphoric gas.

Four proportions of the acid contain four
proportions of phosphorus, and four of oxy-
gene ; two proportions of water contain four
proportions of hydrogene^ and two of oxygene.
The six proportions of oxygene unite to three
proportions of phosphorus to form three of
phosphoric acid, and the four proportions of
hydrogene combine with one of phosphorus to
form one proportion of hydrophosphoric gas ;
and there are no other products.

10, Phosphorus and sulphur are capable of
combining ; they may be united by fusing them
too-ether in a tube exhausted of air, or under
water; but in the last case they must be used
only in small quantities ; as at the moment of
their action water is decomposed, sometimes
with explosions. This compound, which has
been called sulphuret of phosphorus, was de-
scribed by Margraaf in 1762. He formed it of
equal parts of the two substances, but phos-
phorus and sulphur may be united into ©ne
mass in a variety of proportions ; and these
mixtures are more fusible than either of their
constituents. The most fusible compound I
have found, is that formed by the two bodies
united in the proportion of one and a half of

I

[ m ]

sulphur, to two of phosphorus. This remains
liquid at 40" of Fahrenheit ; and would appear
to be composed of one proportion of sulphur
SO, and two of phosphorus 40. When s(;lid its
colour is yellowish-white. It is more combus-
tible than phosphorus, and rises undecoraposed
by a strong heat.

The points of fusion and evaporation of phos-
phorus and sulphur, are so near each other, that
it is not easy to ascertain the difference between
true chemical combinations of these bodies in dif-
ferent proportions, and mixtures of the chemical
compounds, with the bodies themselves ; 8 parts
of phosphorus in weight united to one of sul-
phur, remain fluid at 68^ of Fahrenheit; and
1 of phosphorua with 3 of sulphur, congeal at
about IOC.

11. When phosphorus is fused and exposed
to the action of the Voltaic spark, taken by
means of platina wires, phosphuretted hydro-
gene in small quantities is produced from it ;
but there are no proofs that hydrogene is essen-
tial to its existence ; and phosphorus in its
common state, may contain a minute portion of
the hydruret of phosphorus mixed with it;
it would be very difficult to detect in phospho-
ric acid, the small quantity of water that this
hydrogene would produce; and the red colour
■which phosphprus sometimes possesses, seem*

to be owing to an admixture of small quantities
cf oxide of phosphorus. There are some ana-
losies that favour the idea of the compound
nature of phosphorus, which will be discussed
in the progress of this work ; but in the arrange-
ments of the facts oF the science, it must be still
regarded as an undecompounded body.

12. Phosphorus has not as yet been applied
to any of the purposes of the common arts ;
but various preparations of it are employed for
producing quick inflammation. One of the
best, is a sulphuret of phosphorus, containing
two of phosphorus to one of sulphur ; a little
of it applied to a common brimstone match, in-
flames when gently rubbed.

V. Of Carbon or Charcoal, and the Diamond.

I. The name carbon, signifies the pure in-
flammable part of charcoaL lamp-black, and
other similar substances. The purest known
form in which it can be obtained, is by passing
oils or spirits of wine through ignited tubes.
It then appears as an impalpable black powder ;
it has no tasle nor smell ; it is a conductor of
electricity ; it is more than twice as heavy as water.
For the common purposes of experiments, the
charcoal of light wood, such as the alder, that
has been exposed to boiling water, and after-
wards ignited to whiteness, is sufficiently pure.

. [ 300 ]

Such charcoal, however, rapidly attracts mois-
ture from the atmosphere, so as to increase in
weight from 12 to 14 per cent., and when dry,
absorbs several times its volume of any gas to
which it may be exposed, and it must there-
fore be employed immediately after ignition,
and whilst yet warm.

Carbon, whether coherent in charcoal, or in
powder, is infusible by any heat that has hi-
therto been applied. I have exposed it to the
powers of intense ignition of different Voltaic
batteries; that of Mr. Children, mentioned page
151, one of 40 double plates of 18 inches
square, and the battery of 2000 double plates
of 4 inches, both in vacuo, and in compressed
gasses, on which it had no power of chemical
action. A little hydrogene was given off from
it, and it slowly volatilized in these experiments,
and the part remaining was much harder than
before, so as in one case to scratch glass, and
the lustre was greater ; but its other properties
were unaltered, and there was no appearance
of fusion. Its capacity for heat, according to
Dr. Crawford, is to that of water as .2631 to 1.

2. There are two distinct combinations of
carbon and oxygene, which have been referred
to page 105.

Carbonic acid is formed whenever charcoal
©r carbonaceous matter is burnt in air or

[ 301 1

oxygene, and it is evolved during fermentation^
by the decomposition of animal or vegetable
substances and from limestones by ignition, or
the action of acids.

The most expeditious mode procuring it for
chemical purposes, is by the action of weak so-
lution of muriatic acid on powdered marble.
It may be collected over v/ater, or, for accurate
experiments, over mercury.

Carbonic acid gas was the first elastic fluid
certainly distinguished from air ; the know-
ledge of its acid nature is owing to Dr. Black,
who discovered it in 1755. Mr. Lavoisier,
nearly 30 years afterwards, ascertained its
composition.

Carbonic acid gas extinguishes flame, has a
peculiar sharp taste, and a faint but agreeable
smell. It is not respirable. Its specific gravity
is to that of hydrogene as £0.7 to I. 100 cubi-
cal iaches weigh at the mean temperature and
pressure, 47 grains,

Carbonic acid gas is absorbed by water,
which unites to its own volume of the gas at
41°. By heat it is expelled from the water.

If carbonic acid gas be poured from one
vessel into another vessel containing a lighted
taper, the flame is extinguished.

It reddens litmus paper, and combines with
alkalies, alkaline earths, and metallic oxides.

[ 302 ]

A syntlietical proof of the composkion of
carbonic acid gas, has been already given,
page i05.

Common charcoal, even whe*i very well
burnt, contains a little hydrogene, and affords
a minute quantity of water in its combustion ;
but the charcoal from the decomposition of
oils gives carbonic acid gas alone. It burns
when inflamed in dry oxygene with brilliant
scintillations ; there is no perceptible change
in the volume of the gas ; and wiien the pro-
cess is complete, the oxygene is found conver-
ted into carbonic acid g^as.

The proportions of the elements in carbonic
acid gas are easily learnt by the difference be-
tween its weight and that of oxygene. This
difference proves, as has been stated before,
that it must consist of 13 of charcoal to 34 of
oxygene.

The constitution of carbonic acid gas is proved
analytically by its action upon potassium. If
this metal is strongly heated in a retort con-
taining the gas, it takes fire, and burns with a
red light. Charcoal in fine powder is deposited,
the gas disappears, and oxygene is found added
to the potassium.

3. The compound of carbon and oxygene,
containing less oxygene than carbonic acid gas,
may be formed in many modes besides that

described in page 105; as by igniting chalk or-i
any substance containing carbonic acid with
charcoal, iron, or tin ; or by igniting difficultly
reducible metallic oxides with charcoal, or by
passing carbonic acid gas over charcoal heated
to whiteness, in a porcelain tube. In this last
case, the composition of the gas is shewn by
the circumstances of the experiment, charcoal
disappears, and the carbonic acid becomes car-
bonic oxide gas, and there is a considerable
expansion. The true nature of this elastic fluid
was discovered by Mr. Gruikshank in Marcbj
1801.

Carbonic oxide may be purified from the
carbonic acid with which it is usually mixed,
by washing in lime water.

It is corabustibie, and by the contact of an
inflamed or ignited body, burns in the atmos-
phere with a lambent blue flame. Its specific
gravity, according to Gruikshank, is to that of
hydrogene as 1 3.2 to 1. 100 cubical inches
weigh about 30 grains. •

Carbonic oxide may be taken into the lungs^
but is fatal to animal life. I once took three in-
spirations of it mixed with about ^ of common
air ; the effect was a temporary loss of sensation,
which was succeeded by giddiness, iigkness,
acute pains in different parts of theisody, and

[ 304 ]

eictreme debility ; some days elapsed before!
entirely recovered.

Water absorbs about -^^ of its bulk of car-
bonic oxide.

Chlorine has no immediate action on carbonic
oxide, when they are exposed to each other in
common day light over dry mercury ; not even
when the electric spark is passed through them*
M. M. Gay Lussac, Thenard, and Murray,
have asserted that they do not act on each
other even when long exposed to the direct
solar beams. But experiments which I have
seen made by my brother, Mr. John Davy,
prove the contrary ; they rapidly combine
under this circumstance, and when in equal
volumes, are condensed to one half ; and form
a peculiar gas, which he has discovered is pos-
sessed of very curious properties, approaching
to an acid in its nature.

The nature of carbonic oxide, and the pro-
portions of its elements, are easily demonstrated
by analytical experiments. When two in vo-
lume of it are mixed with one in volume of
oxygene, and an electrical spark passed through
the mixture, an inflammation takes place, and
two in volume of pure carbonic acid are formed,
and there is no other product.

When potassium is strongly heated in it,

t 305 ]

combustion takes place, charcoal is depositee!,
no gas is disengaged, and oxygeiie is added to
the potassium.

From the experiments on carbonic acid and
carbonic oxide, it is evident that the number
representing carbon is about 1 1.4 ; and carbonic
acid is represented by 30 added to 11.4, or
41.4 I anti carbonic oxide by I5 added to 11. 4,
or by 26.4.

Some chemists have been perplexed to find
a .reason why carbonic oxide, which contains
more carbon, is lighter than carbonic acid; but
as Mr. Dalton has ingeniously and justly ob-
served, there is no dsfEculty in this circum-
stance ; carbon in the gaseous state, is probably
considerably lighter than oxygene. The specific
gravity of gasses bears no relation to the den-
sity of the fluids or solids, from which they are
"formed ; ether is lighter than water ; but the
vapour rising from it is much heavier than
■steam. If carbonic oxide be supposed to be.
constituted by equal volumes of gaseous car-
bon and oxygene, occupying the space of two
In volume, then the specific gravity of gaseous
carbon -will be to that of oxygene as I3 to
,17 ; or if the constitution of the carbonic oxide
is similar to that of tjie nitrous oxide, it will be
only as 6.5 to I7.

4=. No compound of carbon and chlorine

VOL, I. X

[ S06 ]

lias been as yet discovered. They have no
action on each other under any circunristances
to which they iiave been exposed.

5. There are two compounds of carbon and
hydrogene, which are perfectly distinct and well
characterized bodies.

One of ihem, which has been called carbu'
retted kydrogene, is disengaged in certain natural
operations, particularly during the decomposi-
tion of vegetable substances; it is the gas evolved
in stagnant waters. It maybe procured by the
distillation of coal that burns with flame, and
by decomposing the salt called acetite of potash
by a red heat; it should be washed with lime
Vk'ater to separate it from carbonic acid.

It burns with a bright yellowish flame. It
has no taste, but a disagreeable empyreumatic
smell. Water aborbs about -^^ of its volume.
Its specific gravity, in its purest form, is to that
of hydrogene as rather less than 8 to 1. 100 cu-
bical inches weigh about 17 grains.

When one of this gas in volume is mixed
with two of oxygene gas, and an electrical spark
passed through them over mercury ; water and
about one in volume of carbonic acid are the
products. Hence one in volume of carburetted
hydrogene must contain two in volume of hy-
drogene gas, and as much carbon as will form
a volume of carbonic acid. This likewise is

[ 307 ]

shewn by the phasnomeiia of its electrization.
When points of platina are electrically ignited
in it, or sparks passed through it, charcoal is
deposited, and double its volume of hydrogene
is produced. When it is mixed with twice its
volume of chlorine over mercury, and acted on
by the electrical spark, an inflammation takes
place, charcoal is deposited, there is a consi-
derable expansion, and about four volumes of
muriatic acid gas are produced;

It is evident from these different results that
carburetted hydrogene may be considered as
composed of one proportion of carbon 1 1.4, and
four of hydrogene 4, and the number represent-
ing it will be 15«4.

6i When a mixture of four parts of oil of
vitriol and one part of strong spirits of wine, or
alcohol is heated in a retort, a gas is generated,
which, when washed by water, is found to be
a peculiar gaseous compound of carbon and
hydrogene; it has been called olefiani gas, and
likewise super carburetted hydrogene. It burns,
when kindled, with a beautiful white flame of
intense splendour. According to Dalton, water
absorbs |- of its volume of the gas. Its specific
gravity is to that of hydrogene nearly as 13 to
1; 100 cubical inches of it w^igli betv/een 29
and 30 grains.

When it is mixed with an equal volume of

[ SOS ]

clilorinej the two gasses condense each other,
and a peculiar fluid is formed, which has been
supposed to be an oil; but -which is a peculiar
compound, not soluble in water, and composed
of hydrogene, carbon, and chlorine. The na-
ture of olefiant gas may be easily demonstrated,
and likewise the proportion of its elements. If
pure sulphur be sublimed in the gas in a glass
tube over mercury, there is a great expansion ;
sulphuretted hydrogene is formed, and char-
coal deposited ; one volume of gas forms about
two in volume of sulphuretted hydrogene: the
sulphur must not be used in much larger quan-
tity than is sufficient to unite to the hydro-
gene; for in this case, by the long application of
heat, the volume is more than doubled ; two
grains of sulphur and a cubical inch of gas are
proper proportions.

The gas is decomposed by electrical sparks ;
one volume of it expands to about two; char-
coal is deposited, and the expanded gas is found
to be hydrogene.

It detonates with great violence by the elec-
trical spark, when mixed with three times its
volume of oxygene; water and nearly two
volumes of carbonic acid are formed in this
process.

When it is detonated with an equal volume of
oxygene, it expand^ greatly, and the twQ gasses

[ 309 ]

together become more than three volumes and a
half. In this case only the -i or ^ of a volume
of carbonic acid gas is formed, but more than a
volume and a half of carbonic oxide 5 a little
hydrogene is consumed, but the greatest part
remains untouched and mixed with the carbonic
oxide ; and it may be separated by combustion
with chlorine.

If an experiment of this kind could be made
without the production of any carbonic acid, or
the consumption of any hydrogenej the volume
of the gasses would be exactly doubled, and
they would consist of equal parts of carbonic
oxide and hydrogene.

It is evident from all these experiments that
olefiant gas may be considered as constituted
by two proportions of carbon 22.8 and 4, of
hydrogene 4, and the number representing it
is 26.8: and supposing a double volume of
gaseous carbon in olefiant gas, its specific gra-
vity will be found to be the same as from the
data presented by carbonic oxide.

7. Most of the gasses that form carbonic acid
in burning were noticed by Dr. Priestley, who
confounded them under the general name of
heavy inflammable air. Oie&ant gas was first
described as a specific sobstaoce, in 11945 by
BondtjDeiman and a Society of Dutch chemists^
Mr* Berthollet and Mr. Murray suppose that

[ Slo ]

there is a great variety of gasses which consist
of oxygene, hydrogene, and carbon, in different
proportions ; but the experiments of Mr. Dal-
ton, Dr. Henry, and Dr. Thomson, are entirely
opposed to these views ; and the researches
which 1 have made in conjunction with my
brother, Mr. John Davy, have convinced me of
the correctness of Dr. Henry's opinion, that
what iiave been called different oxicarburetted
Ji/drogene gasses are merely mixtures of olefiant
gas, carburetted hydrogene, carbonic oxide, and
hydrogene gasses. We used chlorine for separat-
ing olefiant gas at common temperatures, and the
same substance for separating hydrogene by ex-
plosion, or the action of light; and sulphur for
decomposing the carburetted hydrogene; and in
these modes of analysis our results were une-
quivocal.

8. Carbon and azote have no known action
on each other.

9- I have already referred to the alcohol of
sulphur. This substance was supposed by
M. M. Clement and Desormes to be a compound
of carbon and sulphur ; there can be no doubt
from what has been stated, that this idea of its
composition is incorrect : I have found it, how-
ever, sometimes to contain a minute quantity of
charcoal ; and there may possibly be a triple
compound of carbon, sulphur, and hydrogene.

[311]

Sulphur is very soluble in oils and other com-
pounds which consist principally ofhydrogene
and carbon. The charcoal used for making
the alcohol of sulphur always produces sulphu-
reous acid by burning, though previously ex-
posed to a strong red heat, and affords sulphur
to a strong solution of alkali ; but the quantity is
very minute, and it may be questioned whether
the sulphur is not in combination with the
earthy or alkaline matter the charcoal contains;
and no certain deiinite compound of sulphur
and carbon can be as yet admitted in the arrange-
ments of the science.

10- Phosphorus has been supposed capable
of uniting; to carbon ; but in cases when speci-
mens of phosphorus afford charcoal it is most
probably mixed with the substance, or in triple
combination with oxygene and hydrogene; and
no distinct action of the two bodies, and no
definite compound of them has as yet been
described. .

11. A number of forms of carbon are found
in nature : one of the most interesting: of them
is the diamond; the properties of this stone are
well known, it is the hardest of the gems, and
is usually crystallized, often in the form of a
six-sided prism terminated by a six sided pyra-
mid: its specific gravity is about 3.5; it does
not conduct electricity. Of all known bodies

[ 312 ]

it bas the greatest power of refracting light.
When the diamond is strongly heated in air, it
consumes away : and if it be exposed to oxy-
gene continuously ignited by a burning glass,
or by other means, it acts upon the oxygene
nearly in the same manner as charcoal. The
volume of the oxygene is not perceptibly
changedj and it is found converted into car-
bonic acid. M. Lavoisier first determined that
carbonic acid was formed from diamond; and
Messrs. Tennant, Allen, and Pepys, have de»
monstrated by some refined experiments that it
produces about the same quantity as an equal
weight of charcoal. Hence it has been concluded,
that the diamond, is pure carbon, differing from
charcoal merely in the arrangement of its parts.
When it is considered, however, that charcoal
as a conductor and diamond a nonconductor of
electricity, and that their physical properties
difier entirely, it is impossible to receive this
conclusion without doubt. I found that dia-
mond powder heated strongly with potassium
became blackened; and an effect was produced
on the metal similar to that which the absorp-
tion of a niioute quantity of oxygene would
occasion ; this would lead to the suspicion that
there may be a little oxygene in diamond ; but
new experiments are wanting to prove this, and
the quantity^ if any, must be very minutCj which

[ 313 ]

does not harmonise with the doctrine of definite
proportions. If it should be ultimately found
that the diamond is merely pure carbon, it will
be an argument in favour of the varieties of
elementary forms being produced by different
iiggregations or arrangements of particles of the
same matter ; for it is scarcely possible to fix
upon bodies less analogous than lamp black,
and the most perfect and beautiful of the gems.

12. Plumbago or black lead, and anthracite
cr stone coal, are both tolerably pure forms of
the carbonaceous element. In plumbago the
carbon is united either chemically or mechani-
cally to about -^-j- of iron ; in anthracite with
small quantities of earthy matter. In the an«
thracite of Kilkenny in Irelandj the texture is
often fibrous, and the substance has all the
characters of well burned charcoal. In Hamino;
coal the carbonaceous element is united to
bitumen.

1 3. Few substances are more importantin civi-
lized life than the different forms of carbon ; in
their various uses they are essential to the com-
forts and well being of society, and are neces-
sary in almost all the useful arts and manufac-
tures.

The inflammable gasses produced by the
distillation of pit^coal have already been si3c=-
cessfully used in manufactories for the purpose

[ 314 ]

©f affording light, and the application is at once
safe and ceconomical.

In nature the carbonaceous element is con-
stantly active in an important series of opera-
tions; it is evolved in fermentation and com-
bustion, in carbonic acid ; it is separated from
oxygene in the organs of plants, is a principal
element in animal structures, and is found in
different forms in almost all the products of
organized beings,

VL Of Boron* or the Boracic basis.

I. There is a white crystalline substance found
native in volcanic districts called boracic acid. It
may be procured artificially from borax by heat-
ing it in oil of vitriol diluted with eight times
its weight of water; it is difficultly soluble in
water, and may be separated by a fiitre of cloth
or paper. When this substance, slightly mois-
tened, is exposed between two surfaces of pla-
tina, electrified by a Voltaic battery of not less

* In my first paper on this substance I named it boraciutHj
for I supposed that in its pure form it would be found to be
metallic ; subsequent experiments have not justified this conjec-
ture. It is more analogous to carbon than to any other substance;
and I venture to propose Boron as a more unexceptionable
name ; the termination in um having been long used as cha-
racteiistic of a metal. M. IM. Gay Lussac and Thenard have
proposed to call it Bore, a word that cannot with propriety be
adopted in our language, though short and appropriate in the
FresKh nomenclature.

I

[ 315 ]

tlian 100 double plates; a dark coloured sub-
stance separates on the plate negatively electri-j
fied. This substance is boron, or the basis of
the boracic acid. In this way it can be pro-
cured only in very minute quantities, and to
obtain it for the purposes of experiment, bo-
racic acid that has been long exposed to a red
heat, is powdered and strongly ignited with an
equal weight of potassium, in a tube of iron
or copper. The result is exposed to diluted
muriatic acid, and washed with it till nothing
remains but a dark powder, which, when dried
at a red heat, is the substance in question.

2. I first'procured boron in October, I 807,by
the electrical decomposition of boracic acid, and
by potassium, in March, 1808 ; but not in suf-
ficient quantities to examine its properties, or
to ascertain its nature. M. M. Gay Lussac and
Thenard, in June, 180 8, made the experiment
of heating boracic acid and potassium together,
but they did not describe the properties of
boron till the middle of November; and in the
beginning of the same month I had procured
sufficient quantities of the substance to ascertain
its chemical relations. M. M. Gay Lussac and
' Thenard, I believe, recomposed the boracic acid
before me, and oUr experiments were indepen-
dent of each other; but in my first paper on
potassium and sodium read at the Royal Society,

[ S16 ]

in Novemb£r, 1807, at a time when tlie Frencli
cliemists had no idea of the existence of the alica"
line metals, I pointed out the probable applica-
tion of these bodies to the decomposition of the
acids not decompounded.

3. Boron is an opaque, dark olive coloured
powder, infusible, and not volatile at any tem-
perature to which it has as yet been exposed.
When heated strongly in contact with air, it
burns, and forms dry boracic acid. In oxygene
gas it throws off bright scintillations, becooies
coated with boracic acid, and the portion nat
converted into acid, is found darker coloured
than before. When gently heated in chlorine
it emits white fumes, but has no energetic action
on the gas. It is a nonconductor of electricity,
and insoluble in water.

4. That boron combines with oxygene is
shewn by the phcenomena of its combustion.
Boracic acid is the only well known result of
their combination : the preparation of boron
proves that the boracic acid consists of this
body united to oxygene, for oxygene is added
to the potassium in the process. It is very
difficult to ascertain the proportions of boron
and oxygene in boracic acid, for the boracic
acid formed in combustion prevents the process
from going on ; and the black substance^ which
is probably an oxide of boron^ is burnt only with

\

f S17 ]

great difficulty. From comparing the quantity
of potassium required to decompose a given
quantity of boracic acid, witii the quantity of
oxygene absorbed in the, production of the
acid, I am inclined to believe that boracic
acid cannot contain much less than of its
weight of oxygene : I have made a number of
experiments on this subject, but have never
gained perfectly satisfactory results, M. M. Gay
Lussac and Thenard conceive that boracic acid
contains only f of its weight of oxygene ; but
their conclusions were drawn from the action,
of boron on solution of nitric acid, and the eva-
poration of the products; and boracic acid forms
volatile compounds both with water and nitric
acid; for I find that dry nitre and boracic acid
afford by distillation a fluid containing a con-
siderable quantity of boracic acid. From the
quantity of ammonia required to neutralize
boracic acid, it appears that the number repre-
senting it is about 160 : and to destroy the alka-
line properties of 90 parts of potassa requires
twice 160 of boracic acid, so that its acid powers
are extremely feeble.

Boracic acid in its common form is in com-
bination with water ; it then appears as a series
of thin white hexagonal scales ; its taste is very
slightly acid, it reddens vegetable blues. By a
long continued white heat the water is drivea

I

[ 318 1

off from it, and a part of the acid sublimes,
the remaining acid is a transparent fixed glass,
which, rapidly attracts moisture from the air.
The compound of boracic acid and water ap-
pears to contain, from my experiments, about
57 parts of acid to 43 of water. The specific
gravity of the hydrat of boracic acid, as it may
be called, is 1.479, that of the dry acid 1.803.

Boracic acid is very little soluble in water, evea
when boiling ihat fluid does not take up ^''^ of its
weight. It dissolves in alcohol, and gives it
the power of burning with a green flame.

5. Much still remains to be known respecting
the nature and properties of boron, and its com-
binations. Probably a combination of it with
chlorine may be formed. It seems to exert no
action on any of the inflammable bodies except
sulphur, which dissolves a little of it by a long
continued heat, and gives a green tint.

It has hitherto been obtained in quantities
too small to ascertain whether it will have any
applications to the arts.

1

[ S19 ]

DIVISION V.

OF METALS; THEIR PRIMARY COMBINA-
TIONS WITH OTHER UNDECOMPOUNDED
BODIES, AND WITH EACH OTHER.

I. General Observations,

1. The metals form a numerous and most
important class of natural bodies ; they are con-
nected with each other by close analogies, and
by remote analogies to the inHammable solids
described in the |)receding pages; the number
of metals known, or the existence of which may
be presumed, amounts to S9. The characteristic
properties of the metals are a high degree of
lustre, opacity, combustibility, and the power
of conducting electricity. A considerable de-
gree of specific gravity was formerly considered
as an essential character of metallic substances j
but I have discovered bodies lighter even than
water, which agree in all other essential quali-
ties with metals, and which consequently must
be arranged with them. In the order of classi-
fication to be adopted in the following pages,

I Si20 ]

the most ioflaramable metals will be the first
considered: though of recent discovery ihtf
are the most important as agents of analytical
chemistry, and have offered the means of re-
ducing other substances to the metallic form.
The most inflammable metais produce alkalies,
alkaline earths, and earths in combustion. Other
metals afford the substances called oxides, which
are analogous to earths ; and a few are converted
into acids. The metals that produce alkalies
are potassium and sodium : the alkaline earths
are formed from metals, which have been called
barium, strontium, calcium, and magnesium.
The metals supposed to be contained in com-
mon earths are silicium, alumium, zirconium,
ittrium, and gluciura. The metals that produce
oxides are manganese, zinc, tin, iron, lead, an*
. timony, bismuth, tellurium, cobalt, copper,
nickel, palladium, uranium, osmium, tungsten,
titanium, columbium, cerium, palladium, iri-
dium, rhodium, mercury, silver, gold, and pla-
tina. The metals that produce acids are arsenic,
molybdenum, and chromium,

2. The metals differ considerably in their
mechanical properties, in degrees of hardness,
ductilityj and tenacity; all of them that are
fusible by common means assume regular crys-
talline forms by slow cooling, and these forms
are usually cubical or octoedral. The common

[ 321 ]

metals in consequence of their fusibility, mallea-
bility, hardness, and durability, have been the
most important instrument of the arts; the uses
of them have been essential to the progress of
civilization ; and most of the comforts, and many
of the luxuries and refinements of social life are
connected with their applications,

2' Of Potassium.

1. There is a body usually called potash or the
vegetable alkali, which may be thus procured:
quick lime is mixed with solution of wood-ashes,
and boiled for some time with it. The liquor
so obtained, after being passed through bibulous
paper, is evaporated till a solid matter remains;
this solid matter is heated with alcohol or pure
spirit ; the spirit is separated by distillation
in a vessel of silver ; a fusible solid mass is
produced, which is the substance in question.

To form potassium, this substance in a thin
piece, is placed between two discs of platina
connected with the extremities of a Voltaic ap-
paratus of 200 double plates ; it wilHoon under-
go fusion, oxygene will separate at the positive
surface, and small metallic globules will appear
at the negative surface, which consist of potas-
sium. I discovered this metal in the beginning
of October 1807.

2. It may be procured by chemical means

VOL. I, Y

[ 322 ]

without electricity. If iron turnings be heated
to whiteness in a curved gun-barrel, and potash
be melted and made slowly to come in contact
with the turnings, air being excluded,* potas-
sium will be formed, and may be collected in a
cool part of the tube; this method of procuring
it was discovered by M. M. Gay Lussac and
Thenard, in I808. It may likewise be pro-
duced by igniting potash with charcoal, as M.
Curaudau shewed in the same year.

3. Potassium is possessed of very extraor-
dinary properties; it is lighter than water, its
specific gravity is between 8 and 9, water being
10. It is a solid at common temperatures ; it is
very soft, and easily moulded by the fingers. It
fuses at about 150° Fahrenheit, and rises in
vapour, in a heat a little below that of redness.
It is perfectly opaque. Its colour is white, like
that of silver when it is newly cut, but it rapidly
tarnishes in the air ; and to be preserved from
change must be kept under naphtha. It is a
conductor of electricity. When thrown upon
water it acts with great violence, swims upon
the surface, and burns with a beautiful light,
which is white mixed with red and violet; the
water in which it burns is found alkaline, and
contains a solution of potassa. It inflames
when gently heated in the air, burns with a

* See Plate VI, fig. 26.

[ 32S ]

t

red light, and throws off fumes, which are alka-
line. It burns spontaneously in chlorine with
intense brilliancy.

It acts upon all fluid bodies containing water,
or much oxygene, or chlorine ; and in »its ge-
neral powers of chemical combination may be
compared to the alkahest, or universal solvent
imagined by the alchemists.

4. Potassium combines with oxygene in dif-
ferent proportions. When potassium is gently
heated in common air or in oxygene, the result
of its combustion is an orange-coloured fusible
substance ; and for every grain of potassium con-
sumed, about a cubical inch and of oxygene
disappear. To make the experiment accu-
rately the metal should be burnt in a tray of
platina covered with a coating of the salt called
in the French nomenclature, muriate of potash,
a substance immediately to be described, which
may be easily done by fusing it in contact with
the platina. This salt is one of the few substances
that has no action on potassium or its oxides.

The substance procured by the combustion
of potassium at a low temperature, I had ob-
served in October, 1807, but I supposed it to
be the oxide of potassium containing the smallest
quantity of oxygene, for it effervesced in water ;
M. M. Gay Lussac and Thenard, in IS 10,
first demonstrated its real nature, md shewed

C 324 ]

that it was the combination of oxygene and
potassium containing the largest quantity of
oxygene.

The gas produced by its effervescence with
water is oxygene. When it is fused and brought
in contact with combustible bodies, they burn
with vividness. When it is heated in carbonic
acid, oxygene gas is expelled, and it is con-
verted into the compound called subcarbonate
of potash.

When it is heated very strongly upon
platlna, oxygene gas is expelled from it, and
there remains a difficultly fusible substance of
a gray colour, vitreous in its fracture, and
which dissolves in water without effervescence,
but with much heat, and renders the water
alkaline. This substance is pure potash or
poiassa, which was unknown in its uncombined
state till I discovered potassium, but which has
long been familiar to chemists combined with
water in the substance which has been caUed
pure potash ; but which ought to be called the
hydrat of potatsa.

. That the potash obtained by alcohol in the
manner described in the beginning of this sec-
tion, is a compound of potassa and water, is
shewn by many experiments. If it be made to
act upon iron turnings at a dull red heat, the
iron becomes combined with oxygene, hydro-

[ 325 ]

gene is given ofF in abundance, and the alkali
loses its easy fusibility, becomes harder, more
opaque, and of greater specific gravity. In
producing potassium in the experiment of act-
ing upon white hot iron turnings by common
potash, hydrogene is disengaged in abundance
from the decomposition of the water in the
potash ; and I have procured this water by
heating together the potash prepared by alcohol
and boracic acid ; 100 parts of potash treated
in this way gave between 17 and 18 parts of
pure water.

Potassa entirely free from water may be pro-
cured by other means besides the decomposition
of the orange oxide of potassium, or the action
of iron on common potash ; fo'r instance, by
acting on potassium by a small quantity of
water, or by heating potassium with common
potash. The proportion of oxygene in potassa
is learned by the action of potassium upon
water : 8 grains of potassium produce from
water about 9 cubical inches and a half of hy-
drogene ; and for these there must be added to
the metal four cubical inches and three quarters
of oxygene,

5. It has been mentioned, page 114, that the
number representing potassium is 75: and it
appears from the experiments that the orange
oxide of potassium must consist of 1 proportion

[ 326 ]

of potassium 75, and 3 of oxygene 45 ; and the
number representing it is 120. Potassa must
consist of one proportion of potassium 75, and
one of oxygene 15, and the number representing
it is 90. Hydrat of potassa, or the potash pre-
pared by alcohol, must contain one proportion
of potassa 90, and one of water 1 7,*

6. When potassium is heated strongly in a
small quantity of common air, the oxygene of
which is not sufficient for its conversion into
potassa, a substance is formed of a grayish
colour, which, when thrown into water, effer-
vesces without inflaming. This substance is
likewise generated in experiments on the pro-
duction of potassium by iron and hydrate of
potassa, when a little common air is admitted
into the barrel. It is doubtful whether it be a
mixture of potassa and potassium, or a combina-
tion of potassium with a smaller quantity of
oxygene than exists in potassa, that is a prot-
oxide of potassium. If a protoxide of potas-
sium, it probably contains two proportions of
potassium and one of oxygene.

* In the few experiments that I have. made on hydrat of
potassa, there has been rather more water indicated, between
17 and 19 psr cent.; but the potash I used was, I doubt not,
aduherated with a little soda, as no particular care was taken
to purify it, and hydrat of soda contains more water in pro-
portion: and there is great, reason to believe that 90 and 17
a;:e the true estimation. . M. M. Gay Lussac and Thenard
allow about I of water in potash.

[ 327 ]

7. I have already referred to the action of
potassium and chlorine; the inflammation pro-
duced when thin pieces of potassium are intro-
duced, into chlorine is very vivid: potassium
separates chlorine from hydrogene and phos-
phorus with inflammation ; and when potassium
is made to act upon sulphurane there is a vio-
lent explosion; The attraction of chlorine for
potassium is much stronger than the attraction
of oxygene ; potassa, and the orange oxide of
potassium, are immediately decomposed by
chlorine, the chlorine combines with the metalj
and the oxygene is set free.

The combination of chlorine and potassium
is the substance which has been improperly
called muriate of potash, and which, in common
cases, is formed by causing muriatic acid and
solution of potassa to act upon each other, and
by heating the mixture to redness; in which
case the hydrogene of the acid, and the oxy-
2;ene of the alkali are set free as water ; and the
metal of the alkali and the chlorine of the acid
combine. From various analytical experiments
it appears that muriate of potash, which may
be called potassane, consists of 75 of potassium
and 67 of chlorine, and the number represent
ing it is 140. Potassane is the only known
combination of potassium and chlorine.

8. There appears to be a gaseous combination
of potassium and hydrogene ; for I found that

t ] '

■when potassium is heated strongly in hydra-^
gene the gas contracts in volume, and becomes
spontaneously inflammable, and gives alkaline
fumes in its couibustion. M. M. Gay Lussac
and Thenard state that there is a solid com-
pound of hydrogene and potassium, which may
be obtained by heating the metal for a long
while in the gas, at a temperature just below
that of ignition. They describe it as a grayish
solid, and state that it gives off its hydrogene
by the action of mercury. As yet no experi-
ments have been made on the proportions in
which hydrogene and potassium combine.

g. Potassium and sulphur combine with
great energy when they are heated together,
producing much light and heat, even when the
experiment is made out of the contact of air.
The sulphuret of potassium is of a dark gray
colour ; acts with great energy upon water,
producing sulphuretted hydrogene, and burns
brilliantly when heated in the air, becoming
the salt called sulphate of potash. From my
experiments there is every reason to believe
that this compound consists of one proportion
of sulphur 30, and one of potassium 75, and
the number representing it will be 105. Potas-
sium has so strong an attraction for sulphur
that it rapidly separates it from hydrogene j
and potassium heated in sulphuretted hydro-
gene takes fire and burns with great brilliancy^

[ 329 ]

and sulphuret of potassium is formed, and by-
dro2:ene set free,

10. Potassium and phosphorus enter into
union produclnglight; buttheyacton each other
with less energy than potassium and sulphur.
The phosphurd of potassium in its common form
is a substance of a dark chocolate colour ; but
when heated with potassium in great excess it
becomes of a deep gray colour, and of consider-
ablelustre, so that it is likely thatphosphorusand
potassium are capable of combining in two pro-
portions; probably the chocolate-coloured sub-
stance contains one proportion of each, and the
dark gray substance two proportions of the metal.

The phosphuret of potassium burns with
great brilliancy when exposed to air, and when
thrown into water produces an explosion in
consequence of the immediate disengagement
of phosphuretted hydrogene.

11. When charcoal is present during the
production of potassium, it usually contains a
small quantity of carbonaceous matter ; and
charcoal that has been heated strongly in con-
tact with potassium effervesces in water, and
renders it alkaline, though previously exposed
to a temperature at which potassium rises in
vapour. These circumstances shew that there is
an attraction, though feeble, between potassium
and caibon; but as yet no compound of the

I

[ 330 ]

two bodies of which the proportions can be
assigned has been obtained.

12. Potassium like other metals has resisted
all attempts to resolve it into other forms of
matter. Since I first discovered it, and an-
nounced it as an undecorapounded substance,
there has been much discussion respecting its
nature. M. M. Gay Lussac, Thenard, Ritter,
and Dalton, supposed that it was a compound
of hydrogene and potassa; but the first two
chemists have allowed that the phaenomena are
incompatible with such an hypothesis ; in this
case potassium should form liydrat of polassa,
or substances containing water in combustion,
which is not the case ; nor has hydrogene been
in any instance obtained in experiments on
potassium except wlien substances known to
contain hydrogene were present ; and it would
not be more absurd to say that phosphorus is a
compound of hydrogene and phosphoric acid,
than to say that potassium is a compound of
hydrogene and potassa.

13. Potassium, of all known substances, is that
which has the strongest attraction for oxygene ;
and it produces such a condensation of it
that the oxides of potassium are heavier than
the metal itself. Potassium may be used as a
general agent for detecting the presence of
oxygene in bodies ; and a number of substances

C 381 ]

undecomposable by other chemical agents are
readily decomposed by this substance.

The compounds of potassium are of great
use in the arts ; potassa enters into the compo-
sition of soft soap, and the salts having a basis
of potassa are many of them used in medicine.

3. Sodium.

1. Sodium may be procured exactly in the
same manner as potassium, by electrical or
chemical decomposition, the mineral alkali,
or the alkali from the ashes of marine plants
being used instead of pearl ashes. Rather a
higher degree of heat is necessary for its pro-
duction by the action of iron,

I discovered sodium a few days after I dis-
covered potassium, in the year 1 SO 7.

2. In many of its characters it resembles
potassium; it is as vi^hite as silver, has great
lustre, and is a conductor of electricity. It enters
into fusion at about 200° Fahrenheit, and rises
in vapour at a strong red heat. Its specific gra-
vity is between 9 and 10. When heated
strongly in oxygene or chlorine, it burns with
great brilliancy. When thrown upon water it
effervesces violently, but does not inflame, swims
on the surface, gradually diminishes with great
agitation, and rtnders the water a solution of
soda. It acts upon most substances in a manner

[ 332 ]

similar to potassium, but with less energy. I6
tarnishes in the air, but more slowly, and like
potassium it is best preserved under naphtha.

3. Sodium forms two distinct definite com-
binations with oxygene : one is pure soda,
which has long been known, combined with
water, in the substance which has been called
by chemists Soda, but which was not examined
in its uncombined state, till I formed it from the
metal ; the other is the orange oxide of sodium,
which I observed in 180J ; but of which the
true nature was pointed out in 1810 by
M. M. Gay Lussac and Thenard.

Pure soda may be made by burning sodium
in a quantity of air containing no more oxy-
gene than is sufficient for its conversion into
the alkali, i. e. the metal must be in excess : a
strong degree of heat must be applied.

Pure soda is of a gray colour, it is a non-
conductor of electricity, of a vitreous fracture,
and requiring a strong red heat for its fusion.
When a iitde water is added to it, there is a
violent action between the two bodies ; the
soda becomes white, crystalline in its appear-
ance, and much more fusible and volatile, and
is then the substance which has been long
known under the name of soda, but which may,
with more propriety, be called hydiat of soda.

The oxide of sodium may be formed by
burning sodium in oxygene gas in excess. It

[ 333 3

Is of a deep orange colour, very fusible, and a
non-conductor of electricity ; when acted upon
by water, it gives off oxygene gas, and the
water becomes a solution of soda ; it deflagrates
when strongly heated with combustible bodies.

The proportions of oxygene in soda, and
the orange oxide or peroxide of sodium, are
easily learnt by the action of sodium on water,
and on oxygene. If a given weight of sodium,
in a little glass tube, be thrown by means of
the finger, under a graduated inverted jar filled
with water, the quantity of hydrogene evolved
will indicate the quantity of oxygene combined
with the metal, to form soda ; and when sodium
is burnt slowly in a tray of platina, lined with
dry common salt in oxygene in great excess ;
from the quantity of oxygene absorbed, the
composition of the peroxide may be learnt.
From experiments that I have made on this
subject, compared with those made by M. M.
Gay Lussac and Thenard, it appears that the
number representing sodium is 88, and that
soda consists of one proportion of sodium, and
two of oxygene, 88 and 30: the oxide of
sodium, of one proportion of sodium, and 3 of
oxygene, 88 and 43: and hydrate of soda
(soda prepared by alcohol) contains one pro-
portion of sodium, two of oxygene, and two of
water, and the number representing it is 1 5 2.

[ 334 ]

When sodium is kept for some time m a
small quantity of moist air, or when sodium in
excess is heated with hydrat of soda, a dark
grayish substance is formed, more inflammable
than sodium, and which affords hydrogene by
its action upon water. It is probable that this
is sodium in its first degree of oxygenation, or
the protoxide of sodium; but as yet no expe-
riments have been made on its constitution. If
the protoxide, it is likely that it consists of one
proportion of sodium, and one of oxygene.

4. Only one combination of sodium and
chlorine is known: it is the important sub-
stance common salt. It may be formed directly
by combustion, or by decomposing any com-
pound of chlorine by sodium. Its properties
are: well known ; it is a non-conductor of elec-
tricity, is fusible at a strong red heat, is vola-
tile at a white heat, and crystallizes in cubes.
Sodium has a much stronger attraction for
chlorine than oxygene ; and soda or hydrate
of soda is decomposed by chlorine, oxygene
being expelled from the first, and oxygene and
water from the second.

Potassium has a stronger attraction for
chlorine than sodium has ; and one mode of
procuring sodium easily, is by heating together
to redness common salt and potassium. The
compound of sodium and chlorine has been

I 335 ]

called muriate of soda, in the French nomen«
clature; for it was falsely supposed to be com^
posed of muriatic acid gas, and soda ; and it is
a curious circumstance, that the progress of
discovery should have shewn that it is a less
compounded body than hydrate of soda, which
six years ago was considered as a simple sub-
stance, and one of its elements. According to
th^ nomenclature which I have ventured to
propose, the chemical name for common salt
will be sodane.

Common salt consists of one proportion of
sodium, 88, and two of chlorine, 134 ; and the
number representing it is 222 : when the proper
corrections are made, the most accurate analyses,
particularly those of Dr. Marcet, are found to
agree with this number.

5. There is no known action between sodium
and hydrogene, or azote.

6. Sodium combines readily with sulphur^
and with phosphorus, presenting similar phac-
nomena to those presented by potassium. The
sulphurets and phosphurets of sodium agree in
their general properties with thoseof potassium,
except that they are rather less inflammable.
They form by burning, compounds of sul-
phuric and phosphoric acid and soda, and
therefore must contain two proportions of the
inflammable substances, to one of sodium.

[ 336 ]

7. Sodium, when made from substances con-
taining charcoal, usually affords charcoal by-
combustion ; but as yet no definite combina-
tion of the two bodies has been obtained. No
experiments have been made on the action of
sodium on boron.

8. Potassium and sodium combine with great
facility, and form peculiar compounds, which
differ in their properties according to the pro-
portions of their ingredients. By a small quan-
tity of sodium, potassium is rendered fluid at
common temperatures, and its specific gravity
considerably diminished. Eight parts of potas-
sium, and one, of sodium, form a compound
that swims in naphtha, and that is fluid at the
common temperature of the air. Three parts
of sodium, and one of potassium, make a com-
pound, fluid at common temperatures. A little
potassium destroys the ductility of sodium, and
renders it very brittle, and very soft.

9. The compounds of sodium are of great
importance in the common arts, and are sub-
servient to many of the wants of life. Soda is
the most important ingredient in the diff*erent
species of glass, and in hard soaps. The
glasses are composed of soda united to earths
and oxides ; the soaps consist of soda, united to
oily substances. Common salt is found abun-
dantly in nature ; it exists in small quantities

t S3? 1

In almost all waters and all Soils. It dim'nishes
the tendency of animal or vegetable Siib tances
to, decompose, and probably preserves the
ocean in a state fitted for the purposes of animal
life. It is a part of the nourishment of animals,
and though taken in very small quantities,
feeerns to perform an important part in their
ceconomy.

9. The compounds formed by potassium and
sodium, like the metals themselves, are possessed
of strong resemblances ; they may however be
chemically distinguished by a very simple test ;
the diluted aqueous solutions of the compounds of
potassium, render cloudy the nitro-mui iatic so-
lution of platina, which is not the case with simi-
lar solutions of the compounds of sodium. Most
of the compounds of sodium differ from those
of potassium, in containing double proportions
of the other elements. Potassa contains one
proportion of oxygene only ; soda cotitains two,
and the salts having potassa for their basis,
contain only one proportion of acid, whilst
those having soda for their basis, contain two.
The attl^actions df potassium for all substances
that have been examined, are strongfer than
thtise of sodium ; arid when sodium is procured
frdui GbrtipOunds, by the agency of potassiutn,
I50 parts in weight of potassium, or two pro-

voL. r. Z

[ 338 ]

portions, are required to produce 8^ parts df
sodium, or one proportion.

3' Bariums

1. There is a mineral substance found in
Cumberland, Yorkshirej and other parts of
Britain, called Witherite,or carbonate of baryta.
By dissolving this substance in dilute solution
of nitric acid, evaporating the solution to dry-
ness, and heating the salt obtained to whiteness,
a light fawn-coloured powder is procured,
which is baryta or barium combined with
oxygene. To obtain barium, a quantity of this
substance is made into a paste, with water, and
placed on a plate of platina ; a cavity is made
in the paste to receive a globule of mercury ;
the mercury is rendered negative, the platina
positive, by means of a Voltaic battery, con-
taining about 100 double plates.

In a short time an amalgam will be formed,
consisting of mercury and barium. This amal-
gam must be introduced into a little tube made
of glass free from lead, which must he bent in
the form of a retort, filled with the vapour of
naphtha, and hermetically sealed. Heat must
be applied to the end of the tube containing
the amalgam, till all the mercury has been

[ 339 ]

driven off; there will remain a solid dilFicultly
fusible metal, which is barium,

2- I first gained indications of the decom-
position of baryta, in the end of October 1807,
and I obtained an alloy of it with iron, in.
March 1808. The process of electrifying mer-
cury, in contact with the earth, was pointed
out to me in the course of my enquiries, by
M. M. Berzelius and Pontin of Stockholm,
in May 1808 ; and in the beginning of June in
the same year, I obtained the metal.

3. Barium, as procured by heating the amal-
gam, appeared of a dark gray colour, with a
lustre inferior to that of cast iron. It was
considerably heavier than sulphuric acid, for
though surrounded by globules of gas, it sunk
immediately in that fluid. It instantly became
<;overed with a crust of baryta, when exposed to
air, and burnt with a deep red light, when gently
heated. When thrown into water it effervesced
violently, disappeared, and the water was found
to be a solution of baryta.

Barium as yet has been obtained only in
very minute quantities. I have never possessed
enough of it to ascertain its general chemical
and physical characters, and no experiments
upon it have been published by any other
person.

4. From some results that I have obtained,

[ S40 ]

it seems probable that barium may be procured
by chemical, as well as electrical decomposi-
tion. When baryta, or the salt improperly
called muriate of baryta, ignited to whiteness,
was exposed to the agency of potassium, that
metal being sent through it in vapour, a dark
gray substance appeared, diffused through the
baryta, or the muriate, not volatile, that effer-
vesces copiously in water, and that lo^t its
metallic appearance by exposure to air : — the
potassium in this process was converted into
potassa.

5. Tlie only well kriown combination of
barium, with oxygene, is baryta or baria. It is of
a pale grayish green colour. Its specific gravity
is about 4, that of water being 1. This substance
is a non-conductor of electricity, has a strong
caustic taste, reddens turmeric, and renders
green, vegetable blues. When acted upon by
a small quantity of water, it heats violently,
becomes white, unites to a proportion of water,
and becomes a hydrate. The pure alkaline
earth is infusible, except by an intense heat:
the hydrate fuses at a strong red heat ; a consi-
derable part of its water is expelled by a still
higher temperature. Baryta is soluble at 60°,
in about 20 parts of water, and at 212° in about
2 parts. That baryta is composed of barium
and oxygene, is proved by the combustion of

[ S41 ]

barium in oxygene ; in which, as I have found,
oxygene is absorbed and no product but baryta
formed. It is likewise proved synthetically by
the action of barium upon water, in which case
hydrogene is evolved; and analytically it ap-
pears from the action of potassium, on the
earth. From indirect experiments, I am in-
clined to consider baryta as composed of 89.7
of barium, and 10.3 of oxygene : and sup-
posing the earth to consist of one proportion of
metal an4 one of oxygene, the number repre-
senting barium will be 1 30, and that represent-
ing the alkaline earth will be 14^. >

Barium, as would appear from the experi-
jnents of M. M. Gay Lussac and Thenard, is
capable of combining with more oxygene than
exists in baryta. These able chemists state,
that when baryta is gently heated by a spirit
lamp, in a glass tube filled with oxygene gas,
an absorption of the gas takes place. As yet
no experiments have been made on the pro-
perties of this oxide of barium, or on the
quantity of oxygene it contains : probably
baryta may be easily combined with oxygene,
by heating it with byper-oxymuriate of baryta.
T/ie ky drat of baryta, if its composition be esti*
pnated ^xpm M. JBerthollet's experiments,consists
of one proportion of baryta, and one of water.

6. One combination only of barium and

[ S42 ]

clilorine is known ; it may be formed by beat*
ing baryta in muriatic acid gas, or in chlorine.
In tlie first case, the oxygene of the baryta
produces water by combining with the hydro-
gene of the acid ; in the second it is expelled r
and in an experiment made on purpose, I found
that for every part in volume of chlorine ab-
sorbed, half a part of Oxygene was given off from
the alkaline earth. Hence it may be concluded
that the compound of barium and chlorine
contains one proportion, of meiai 13O and one
of chlorine 67. This substance is fusible by a
very strong heat, is very soluble in water ; its
taste is bitter, its colour white, it is crystalline
Und transparent. It is improperly called in
the French nomenclature, muriate of baryta.
According to the principles of nomenclature
which I have proposed, its name will be barang.

8. No other combinations of barium, except
those with oxygene and chlorine, have been as
yet examined ; there can, however, be little
doubt that its powers of combination will be,
in many respects, analogous to those of potas-
sium and sodium, as, of all metallic substances,
it is the nearest related to these bodies.

9. The compounds of barium have as yet been
applied to the arts in very few cases. Baryta is
employed in small quantities, in the manufacture
of certain kinds of porcelain ; most of the salts

[ 343 ]

containing baryta as a basis, are poisonous.
The combination of baryta and carbonic acid,
made artificially by pouring a solution of
carbonate of ammonia, into a solution of nitrate
of baryta, forms a pigment of a very pure white
colour.

4' Strontium'

1. Strontium may be procured precisely in
the same manner as barium; carbonate of
strontia, or strontianite, a mineral found at
Strontian in Scotland, being used instead of
"witherite. 1 first procured this metal in l8o8,
but in quantities too small to make an accurate
examination of its properties. It seemed very
analogous to barium, had not a very high
lustre, appeared fixed, difficultly fusible, and
not volatile. It became converted into strontia
by exposure to air, and when thrown into
water, decomposed it with great violence, pro-
ducing hydrogene gas, and making the water
a solution of strontia.

Q. One combination of strontium with oxygene
only is at present known ; it is strontia, or stron-
tites, the substance procured by burning stron^
tium. It may be produced in large quantities by
igniting strontianite intensely with charcoal pow-
der, or by heating to whiteness the salt formed
from this fossile, by the action of nitric acid.

[ 344 ]

It appears oF a light fawn colour, and agrees,
in many of its characters with baryta. It is
fusible only by 91) intense heat. Its specific
gravity is between three and four, water being
one. It is soluble in about 200 parts of water,
at common temperatures, and is much more
soluble in hot than cold water; its taste is acrid
and alkaline, it reddens paper tinged with
turmeric. When acted upon by a small quan-
tity of water^ it becomes hot, its colour changes
white, and it is converted into a hydrate,
^nd tlien becomes fusible at a white heat. Fron^
indirect experiments, I am disposed to regard it
3s composed of about §6 of strpntium and I4
pxygene ; and supposing it to contain ope
proportion of metal and pne of oxygene, the
l^umber representing strontium will be go, and
Jh^at representing the earth 103,

TSo experiments have as yet bee« inade
on the direct combination of strontium and
^hloripe ; but ^ substance which appears to
consist of these two bodies, and no other ele-
?nents,may be made, by heating strontia strongly
jn chlorine, or muriatic acid gas, or by igniting
to whiteness the salt formed by the solution of
strontianite in muriatic gcid. By the action
of chloride on strontia, oxygene is expelled : 'by
the action of muriatic acid gas upon it, water is
fprijQgd. fhp cp|aip,9uo^| of clilorifie aiid stron-

t 345 ]

tiiim, or sfroniane^ is a white substance, diffi-
cijltly fusible, fixed in the fire, a non-conductor
pf electricity, and of a peculiar bitter taste ;
when brought in contact with the flame of wax,
tallow, oil, or alcohol, it tinges it of a rose
colour; and this js a distinctive character of
the compounds of strontium ; the salts formed
from it give this tint to flame, those of baryta
give a yellow tint. From direct experiments
I ascertained that 50 parts of strontane con-
sisted of about 29 parts of metal and 21 of
chlorine ; so that it must be regarded as com"
posed of one proportion of strontium, and one
of gas, go and 67.

4. No experiments have as yet been made
on the action of strontium, on any of the other
elementary substances.

6. None of the compounds of this body have
3S yet been applied to any of the purposes of
the arts, and its combinations are rare in
nature.

5. Calcium.

1. Calcium may be obtained by the same
processes as barium and strontium. Mild cal-
careous earth, or chalk being used instead of
-^ilherite and strontianite ; or common well-
burnt lime may be employed for making the
paste, from which the mercurial amalgam is
to be fof med by Voltaic electricity.

[ 346 ]

I first procured calcium about the same time
as barium and strontium, but only in very
minute quantities, so that little can be said
concerning its nature. It appeared brighter
and whiter than these two metals, and burnt,
when gently heated, producing dry lime. I
have had no opportunity of examining its
general physical and chemical qualities.

S. There is onlyone known combination of cal-
cium and oxygene, which is the important suh'
stZLnce Jime or calcia. The nature of this substance
is proved by the phssnomena of the combustion
of calcium ; the metal becomes converted into
the earth, with the absorption of oxygene gas.
When the amalgam of calcium is thrown into
water, hydrogen e gas is disengaged, and the
water becomes a solution of lime ; and from
the quantity of hydrogene gas disengaged,
compared with the quantity of lime formed in
experiments of this kind, M. Berzelius has
endeavoured to ascertain the proportion of
oxygene in lime. The nature of lime may be
also proved by analysis ; when potassium in
vapour is sent through the earth, ignited to
whiteness, the potassium, I have found,
becomes potassa, and a dark gray substance of
metallic splendour, which is calcium either
wholly or partly deprived of oxygene, is found
embedded in the potassa, and it effervesces

[ 3.17 3

violently, and forms a solution of lime, by the
action of water.

Lime is obtained for common purposes, from
marble of the whitest kind, such as the Parian
or Cr.rara marble, by long exposure to a strong
heat. It is a white soft substance, of specific
gravity Q.3. It requires an intense degree of
heat for its fusion, and has not yet been ren-
dered volatile. Its taste is analogous to, but
milder than that of baryta and strontia. It is
soluble in about 45O parts of water, and seems
to be nearly as soluble in cold, as in hot water.
It acts upon vegetable colours in a manner
similar to the other alkaline earths. When water,
in small quantities, is added to it, a consi-
derable heat is produced, a portion of the
water combines with the lime, and it becomes
a hydrate ; but water does not adhere to it
with the same degree of energy, as to baria
and strontia, for it may be expelled by a
strong red heat. From the experiments of
M. Berzelius, and those which I have made, it
appears that lime consists of about 50 of metal
to 7.5 of ©xygene, and the number representing
calcium is 40, and that representing lime 55 ;
and the hydrate of lime must consist of 55 lime
and 1 7 water, which estimation agrees with the
experiments of M. Lavoisier and Mr. Dalton.

[ 348 1

I have attempted to combine lime with more
oxygene, but without success.

3. When lime is heated strongly in contact
with chlorine, oxygene is expelled, and chlo-
rine absorbed ; and, as happens in all the
decompositions of metallic oxides, of which
the metals combine with only one proportion
of oxygene and chlorine, for every two in
volume of chlorine absorbed, a volume of
oxygene is expelled. The substance formed
hy the action of chlorine on Jime, as the
oxygene of the lime is expelled, must evidently
consist of chlorine and calcium. It has been
called dry muriate of lime ; according to the
true view of its composition, it may be called
mtcane. It is a semi-transparent crystalline
substance, fusible at a strong red heat, a non-
conductor of electricity, has a very bitter taste,
rapidly absorbs water from the atmosphere ; and
is extremely soluble in water : by the evapora-
tioi) of its solutiop at a low heat, crystals may
be obtained, which consist of calcane, combined
with more than a third their weight of water.
From my experiments, it appears that calcane
consists of 31 chlorine and 19 of calcium, and
hence it may be supposed to contain one pro-
portion of the metal, and one of the gas, and
the number representing it on this idea is 107 ;

[ 349 ]

And it is evident, from the experiment on tli€
action of clilorine on lime, that the proportion
of oxygene in lime, and of chlorine in calcium,
must be in the ratio of 15 to 67.

4- As yet no experiments have been made oil
the combinations of calcium with any of the
inflammable, or acidiferous substances, or
metah.

5. The compounds of calcium are found
abundantly on the surface of the globe, and are
of great importance in the osconoray of nature,
and in the processes of art. Lime combined
with carbonic acid is an essential part of fertile
lands : a number of rocks are constituted by
this substance. Gypsum or alabaster, is lime
combined with sulphuric acid; and the earth
of bones consists of lime united to phosphoric
acid. There is no animal or vegetable sub-
stance that does not contain larger or smaller
quantities of calcareous matter. The uses of
lime in m.ortar are well known. Ouicklimej
employed as a manure, tends to decompose
and dissolve inert vegetable matter, and ren-
ders it proper for the nourishment of plants;
and in this operation the lime is United to car« (
bohic acid, and becomes a permanent part of
the soil. In the process of tanning, lime is
employed to remove the hair from the skins of
animalsj and it is used in certain opera-

[ 350 ]

rations of bleaching, dyeing, and other useful
arts.

6. Magnesium,

1. Magnesium* may be procured from the
earth called magnesia, wliich is the same as the
calcined magnesia of druggists, by processes
similar to those referred to in the three pre-
ceding sections ; but a much longer time is
required to produce an amalgam of magnesium
and quicksilver, by electrical powers, than to
produce amalgams of the metals of the other
alkaline earths.

I succeeded in decomposing magnesia like-
wise, in the following manner : I passed potas-
sium in vapour through magnesia, heated to in-
tense whiteness, in a tube of platinum, out of the
contact of air ; I then introduced a sm all quantity
of mercury, and heated it gently for some time
in the tube. An amalgam was obtained, which
by distillation, out of the contact of the atmos-
phere, afforded a dark gray metallic film, which
was infusible at the point at which plate glass
softened, and which, in the process of distil-

* In my first paper on the decomposition of the earths,
published in 1808, I called the metal from magnesia, mag-
nium, fearing lest,if called magnesium, it should be confounded
with the name formerly applied to manganese. The candid
criticisms of some philosophical friends have induced me to
apply the termination in the usual manner.

[ 351 1

lation of the mercury, rendered the glass black
at its point of contact with it. This film burnt
when heated strongly, with a red light, and
became converted into a white powder, which
had the character of magnesia : when a portion
of the metal was thrown into water, it sunk to
the bottom, and effervesced slowly, becoming
covered with a white powder; by adding %
little muriatic acid to the water, the efferves-
cence was violent ; the metal rapidly disap-
peared, and the solution was found to contaia
ma2;nesia.

I have made several experiments with the
hope of obtaining larger quantities of magne-
sium, such as might have enabled me to exa-
mine its chemical and physical properties ; but
without success. It is very difficult to procure
a pure amalgam of magnesium by potassium
and mercury ; the heat must be intense ; and at
a high temperature, potassium acts with great
energy upon platina, so that unless the tube is
very solid, it is destroyed in the process, and
when the heat is not very grea.t, potassium
remains in the tube, which is, found afterwards^
in the amalgam. The potassium may however
be separated by the action of water ; which,
even in the amalgam, rapidly converts it into
potassa, but which has a much feebler action
«R magnesium, ^When the amalgam contains

t S5« }

j)otaSsmm,it likewise usually contains p!atinurrfj
which is very soluble in the compound of
potassium and quicksilver.

2. There is only one knowfi compound ormag-
iiesiumand oxygene,whiehis the sitbstaneefronfi
Ivhich the inetal is procured, Magnesia, That
magnesia consists of magnesium and oxygene^
is proved both by analysis and synthesis. Iti
the production of magnesium by potassium^
the potassium is found converted into potassa^
and therefore must have gained oxygene from
the magnesia; and in the formation of mag*
nesia from magnesium, oxygene is absorbed.
No experiments have as yet been made to deter-
mine the proportions of the elements in magne-
sia ; biit from experiments which I have made
on the combinations of this substance with acids,
assuming that they ire single proportions, I am
inclined to adopt 53 as the number representing
it; and if it be supposed to be constituted by
one projiortion of metal, and orie of 03tygene,
the number representing the metal will be 38.

Magnesia appears in its comriion formj as a
white soft powdef ; its specific gravity is be-
tWeen and 3, It is found in nature in the
crystalline form ; specimens have been brought
from North America, which nearly resemble
talc in theit external characters. Magnesia has
scarcely my tftsiej no smell ; it reddens tur-

[ '353 ]

merle. It is infusible, except by the intense
Iieat produced by the combustion of hydrogene
gas in Qxygene, or that generated by Voltaic
electricity. It is scarcely soluble in water, but
produces heat when water is mixed with it,
and it absorbs a considerable portion of the
fluid. When it is procured by the decomposi-
tion of a solution in which it is combined with
an acid, by means of solution of potassa or soda,
it falls down in union with water, as a hydrat;
but the water adheres to it with a very feeble
attraction only, and is expelled entirely at a red
heat. Hydrat of magnesia when dried at 212°,
appears in coherent semitransparent masses,
very brittle and soft ; it contains about ^ of its
weight of water.

3. When magnesia is strongly heated in
contact with chlorine, chlorine is absorbed, and
oxygene expelled, and in the usual proportions
as to volume. Hence it is evident that there
exists a combination of magnesium and chlo-
rine ; though this body, which may be called
magnesane^ has never been examined in a se-
parate state. The salt called- muriate of mag-
nesia, is a compound of magnesane and water,
and when it is acted on by a strong red heat,
by far the greatest part of the chlorine unites
to the hydrogene of the water, and rises in the
form of muriatic acid gas, and the oxygene of

VOL. I. A a

[ 354 ]

the decomposed water combines with the mag-
nesium to form magnesia ; some magnesane is,
however, found mixed with the magnesia,
which affords crystals of muriate of magnesia
by the action of water.

4. No experiments have as yet been made
on the action of magnesium upon any of the
inflammable or metallic substances. ,

5. The compounds of magnesium occur ex-
tensively diffused in nature. Magnesia exists in
certain limestones which are found in different
parts ol Great Britain and Ireland, and which are
less fitted for the general purposes of manure
than common limestone. Magnesia, in its un-
combined state, as appears from the experiments
ot Mr. Tennant, is injurious to plants, but united
to carbonic acid, it seems to form an useful
part of the soil: the magnesian liniestones are
distinguished by their slow solution in acids ;
and they render weak solutions of nitric acid
turbid by their action upon them. Magnesia,
and some of its saline combinations are used in
medicine ; its application in bleaching has been
referred to in an earfy part of this work.

7. Aluminum.

1, When a solution of ammonia or of po-
tassa, not in excess, is thrown into a solution
of alum, a substance falls dov/n, which when

[ 355 ]

well washed, and dried at a red heat, is
alumina. This substance appears to contain a
peculiar metal, but as yet Aluminum has not
been obtained in a perfectly free state, though
alloys of it with other metalline substances
have been procured sufficiently distinct to
indicate the probable nature of alumina. Alo-
mina cannot be decomposed by the electriza-
tion of mercury in contact with it, in the same
manner as the alkaline earths. The first ex-
periment by which I obtained evidcBces of its
composition, was made in 1808. by fusing iron
negatively electrified in contact with it; the
earth was moist in this process, and a very
high Voltaic power was applied. The globule
of metal obtained was whiter than pure iron ;
effervesced slowly in water, becoming covered
with a white powder, and the sohition in mu-
riatic acid decomposed by an alkali, afforded
alumina and oxide of iron.

By passing potassium in vapour, through
alumina heated to whiteness, the greatest part
of the potassium became converted into potassa,
which forme.d a coherent mass with that part of
the alumina not decompounded, and in this mass
there were numerous gray particleSj having the
metallic lustre, and which became white when
heJttedin the air, and which slowly effervesced
in water. In a case in which a similar experi-
ment was made, a strong jed heat only beiag

; . [356]

applied to the alumina, a mass was obtained,
which took fire spontaneously by exposure to
air, an'! wh'ch effer vesced violently in water,
and which probably contained the basis of alu-
mina united to potassium.

2. That oxygens exists in alumina, cannot
be doubted, when the conversion of potassium
into potassa by its action upon it, is considered ;
and that it contains an inflammable substance
united to oxygene, seems likewise evident ; and
that this is metalline in its nature appears ex-
tremely likely, both from the facts detailed, and
from analogy ; but this point cannot as yet be
considered as demonstrated.

Alumina, in the form in which it is usually
obtaintd, has no taste nor smell, adheres strongly
to the tongue, has no action upon vegetable
colours, is insoluble in water, is soluble in all
the mineral acids and in hot solutions of fixed
alkalies When the precipitate from solutions
of alum has been dried only at the temperature
of the atmosphere, it is found combined with
nearly an equal weight of water, and then ap-
pears as a white powder or a gelatinous substance.
There is a native hydrat of alumina found in
different parts of the world, crystallized and
transparent, and which has been called Wavel.
lite : from Mr. Gregor's experiments, and my
own, it appears that this substance contains
about 28 per cent, ©f water, -i.

[ 357 ]

No direct researches have been made on the
quantity of oxygenejn alumina ; but from some
experiments that I made on the quantity of am-
monia required to decompose saturated solutions
of alumina in acids, it would appear that the
number representing alumina is about 48, and
supposing it to consist of one proportion of alu-
minum, and one of oxygene, 33 will be the num-
ber representing aluminum.

3. No substance is known that can be re-
garded as a compound of chlorine and aluminum.
Alumina is soluble in solution of muriatic
acid ; but by heating the salt obtained, muriatic
acid gas rises and alumina remains behind,

4. The compounds of alumina are found
abundantly in the mineral kingdom, and many
of them are of great importance in the common

^.arts. Alumina forms a part of the greater
number of rocks, and is found in larger or
smaller quantities, in almost all soils. In its
crystallized form coloured by small quanti-
ties of iron, it constitutes a beautiful class of
gems, distinguishedvb'y the name Telesiaj in-
cluding the rubyV'the sapphire, the oriental
topaz, and other I ard and brilliant stones.

Alumina combined with silica and other
substances, forms the varieties of porcelain and
chjna-iware. Its acid combinations, are used to
a great extent in dyeing and calico printing fpr
fixing colours on stixfis.

[ 558 ]

8. Glucinum.

1. There is an earth which was discovered
by Vauquelin in 1798, called glucine, orglucina<
It may be obtained from the beryl or the eme-
rald, by the following process ; the stone, in
fine powder, must be ignited for half an hour
in a crucible of silver or platina, willi three
times its weight of hydrat of potassa or soda.
The mass must be dissolved in solution of mu-
riatic acid, and the compound obtained exposed
to heat till it is dry. Water is then added to
itj'and the aqueous solution obtained acted on
by solution of carbonate of potassa ; a white
powder is obtained which must be dissolved in
diluted oil of vitriol not added in excess ; a
little of the salt called vitriolated tartar, or
sulphate of potassa, must be mixed with the so-
lution, and the whole evaporated till it begins
to crystallize ; crystals of alum will form.
When no more can be obtained, the remaining
liquor must be mixed with solution of carbonate
of atnmonia added in great excess ; the mixed
iiquor must be passed through bibulous paper,
evaporated to dryness, and the solid matter
remaining heated to redness, it is then glucina.

2. There is great reason to believe that
gluclria is a compound of a peculiar metallic
substance, which may be called glucinum and
gxygene. The evidence that such is its cona-

[ S59 ]

position, 1 have obtained,^ by heating, it with
potassium in the same manner as alumina ;
the potassium was for the most part converted
into potassa, and dark coloured particles h;'.ving;
a metallic appearance were found diifu^ed
through the mass, which regained the earthy
character by being heated in the air, and by
the action of water, and in this last case hydro-
gene was slowly disengaged.

3, Giucina in its pure form appears as a
white powder without taste or smell, it requires
an intense degree of heat for its fusion; it is
not soluble in water in any perceptible degree,
it does not alter the colour of vegetable blues
or yellows. When it is thrown down from an
acid solution, by an alkali, it exists in combi-
nation with water, as an hydrat. It forms sweet-
tasted salts soluble in water, with the acids, and
hence it gained its name, frofti yxmvg sweet.
From experiments on the quantity of ammonia
necessary to decompose the muriate of giucina,
I am inclined to adopt 54 as the number repre-
senting the earth, and supposing it a protoxide.
39 as the number representing the metal.

4. No compounds have been as yet examined
in which glucinum can be supposed to exist,
uncombined with oxygens. Giucina has not
as yet been applied to any of the purposes
of the arts, and its combinations in nature are
very rare.

E 360 ]

9. Zirconnm.

1. There Is a peculiar earth, which was dis-
covered by M. Klaproth, in 1793-, and which
may be procured from a stone found in Ceylon,
and called the jargon, or zircon, and likewise
from the hyacinth, by the following process'.
The powder of these stones must be ignited
for a long while with hydrat of potassa ; the
substance which is not dissolved by the hydrate
of potassa, is principally zircon. The soluble
matters must be separated by water, and the
insoluble matter boiled in muriatic acid, and
the solution so obtained, evapdrated to dryness,
and heated to the temperature of 212*. An
aqueous solution of zircona in muriatic acid, is
obtained by the action of water on the solid
mass ; and pure zircona is procured by decom-
posing this solution by solution of ammonia,
and heating the powder obtained to redness.

2. There is the same evidence for believing
that zircona h a compound of a metal and oxy-
gene, as that afforded by the action of potassium
on the other earths. The alkaline metal when
brought into contact with zircona ignited to
whiteness, is for the most part converted into
potassa, and dark particles, which when exa-
mined by a magnifying glass, appear metallic
in some parts, of a chocolate brown in others,

- are found diffused through the potassa and tlie
undecompounded earth. .

[361]

3. Zircoria appears as a harsh whitish powder
without taste or smell ; it possesses no action on
vegetable colours, and is insoluble in water ;
its specific gravity is rather above 4. It is fusible
at a lower temperature than any of the other
earths; the heat of a good forge is sufficient to
soften it. In a mass it is very hard and scratches
rock crystal. Zircona is insoluble in water, but
when precipitated from its solution, and dried
at a low temperature, is found in the state of
a hydrat ; and has an appearance like that of
resin or glue, its particles adhere together; the
hydrat contains more than 4- of its weight, of
water, Zircona is soluble in the mineral acids
and in solutions of alkaline carbonates. From
experiments I have made on the comparative
saturating powers of ammonia and zircona, 1 am
disposed to give 85 as the number representing
the earth, and 70 as the number representing
the metal; supposing the earth to be a protoxide.

4. No substance has as yet been formed or
examined, in which zircpnum can be supposed
to exist free from oxygene. It forms a crys-
tallised muriate when dissolved in mnriatic
acid ; but the muriatic acid is expelled by heatj
without any apparent union of chlorine and
the metal. Its combinations therefore must
be objects of future enquiry.

Zircona has not yet been found in sufficient

I

[ 362 ]

quantities, to be applied to any of the purposes
of the arts. It combines with the other earihs,
and forms compounds analogous to porceh\in.

10. Sil'icunu

1. Pure transparent quartz, or rock crystal,
consists almost entirely of a peculiar earth called
silex or silica: this earth raay be procured
from that stone or from common flints by ig-
niting them in powder, with three or four limes
their weight of hydrat of potassa, or soda, in a
silver crucible, making an aqueous sohition of
the substance so obtained, and adding to it any
acid in quantities barely sufficient to neutralize
the alkali, a gelatinous substance separates, which
is silica combined with water : and the pure
earth may be obtained by washing this substance
well, and then igniting it to whiteness.

2. That silica consists of oxv2;ene united to
a peculiar inflammable basis, which is probably
metallic, is shev/n by many experiments. When
iron is negatively electrified, and fused by the
Voltaic battery in contact with hydrat of silica,
the metalline globule procured contains a matter
which affords silex during its solution ; and
when potassium is brought in contact with silica
ignited to whiteness, a compound is formed
consisting of silica and potassa, and black par-
ticles not unlike plumbago are found diffused

through the compound. From some expefL
ments I made, I am inclined to believe that
these particles are conductors of electricity ;
they have little action upon water, unless it
contain an acid, when they slowly dissolve in it
with effervescence; they burn when strongly
heated, and become converted into a white
substance having the characters of silica ; so
that there can be little doubt, both from ana-
lysis and synthesis, of the nature of silica ; but
no direct experiments have as yet been made
upon the proportion of oxygene it contains.

3. Silica is a white powder, very analogous
in its physical characters to the other earths ; iti
its state of hydrate it is soluble in alkaline lix-
ivia, and likewise in acids. It is separated from
the common mineral acids by a very gentle
heat, they rise from it in vapour, but it forms
permanentcompounds with boracic, phosphoric,
and fluoric acids ; its compound with phos-
phoric and boracic acids is a white powder,
that with fluOric acid a permanent gas. From
Some experiments that I have made on the
quantity of' ammonia necessary to decompose
the saturated solution of silica in muriatic
acid, and from the composition of its gaseous
fluoric combination, as ascerfained by my bro-
ther Mr. John Davy, I estimate the number
tepresenting silica as 61 ; and as it seems to
combine with double proportions ol" acids, I

[ 364 ]

am inclined to regard it as a deutexide, com*
posed of 31 basis, and 30 oxygene.

4. No compound of silicum and chlorine is
known ; and as this substance has never been
procured in masses, or even in an insulated
state, its action upon the other undecompounded
substances has not been examined.

5. Silica is one of the earths most generally
diffused in nature. It forms perhaps the largest
part of the solid surface of the globe. It is of
great use in many of the arts ; it is the basis of
glass and porcelain, and the art of manufacturing
these substances depends upon the attraction of
silica for other metallic oxides.

11. Ittrivm.

1. There is a mineral substance called Gado-
linite, found at Itterby in Roslagen in Sweden,
in which a peculiar earth was discovered In
1794, by Mr. Gadolin, and to which the name
of illria has been given. To procure this earth,
the pulverized fossile must be digested for a
considerable time in solution of muriatic acid.
The solution obtained must be evaporated to
dryness, redissolved in distilled water, and
precipitated by caustic ammonia ; the precipi-
tate obtained must be digested with solution of
hydrat of potassa ; the remaining substance
must be redissolved in solution of muriatic acid
^ot used in excess, succinate of soda must be

[ 365 1 .

poured into this solution till all precipltatiorf
is complete ; the filtered liquor must be de-
composed by carbonate of soda, a white powder
will fall down, which when ignited strongly, is
pure ittria.

2. When ittria is treated with potassium in
the same manner as the other earths, similar
results are obtained ; the potassium becomes
potassn, and the earth gains appearances of
metallization, so that it is scarcely to be doubted
that ittria consists of inflammable matter, me-
tallic in its nature, combined with oxygene.

3. Ittria appears as a white powder, without
taste, smell, or power of action on vegetable
colours; it requires an intense degree of heat
for its fusion ; it is not soluble in water. No
experiments have been made to ascertain whe-
ther it forms a hydrat with water, but this is
most probably the case ; its specific gravity is
greater than that of any of the other earths,
being more than 4 5. It combines with the
acids, and forms sweet-tasted salts with those
in which it is soluble. With acetic and sul-
phuric acids it forms crystals of an amethyst
colour. It is not acted upon by solutions of
caustic alkalies ; it is slightly soluble in solution
of carbonate of ammonia.

4>. It is probable that a compound of chlorine
and ittria may be obtained ; but as yet no ex-
periments have been made on any compounds

[ 366 ]

of this substance, except such as contain oxy-
gene ; the proportion of oxygene in ittria cannot
be determined from any experiments hitherto
published. According to Klaproth 55 parts oF
ittria combine with 18 parts of carbonic acid ;
consequently, if it be supposed that the carbonate
of ittria consists of one proportion of acid, and
one of earth, the number representing ittria
wili be I£6; and on the iiypothesis that ittria
consists of one proportion of metal, and one of
oxygene, which is probable from all analogy,
the number representing ittrium will be 111.
. 5. The compounds of ittria are very rare
in nature, and as yet no applications of this,
substance has been made to any of the purposes,
of the arts.

XII. Manganesum.

1. The mineral called manganese has been
referred to, page 227 ; it consists of a peculiar
metal, mangaiiesum united to oxygene. To pro-
cure the pure metal, solution of muriatic acid
mustbe distilled from manganese in fine powder,
the mixture strongly heated, and the pra-
cess repeated till the washings in pure water give
only a white precipitate with a solution of the
salt called prussiate of potassa and iron ; an
aqueous solution of potassa is then added to
the mixture, so as to render it alkaline; the
whole is then poured on a filtre, and the solid

[ 367 ]

matter obtained well washed, dried, mixed with
charcoal powder and oil, and intensel)'- heated
for half an hour in an infusible earthen crucible
lined with charcoal powder ; a number of small
metallic globules will be obtained, which are
o;lobules of manacanesum.

2. Manganesim was first procured in its pure
form by Kaim and Gahn, between 17;0 and
1775. It is of a grayish white colour, it has
not much lustre ; its hardness is nearly that of
iron ; the specific gravity is about 6. 850. It is
very brittle. It requires a higher degree of heat
than iron for its fusion. It immediately tar-
nishes in the air, and becomes gray, brown,
and at last black ; when strongly heated in
contact with ox y gene, it burns with great bril-
liancy, throwiog ofi' vivid sparks; when heated
in chlorine it takes fire and burns. It dissolves
with effervescence in the mineral acids.

3. There are two definite combinations of
manganesum and oxygene, one dark olive, and
one brownish black. The first, or olive o.vide,
may be obtained by ciiss olving common manga-
nese in nitrous acid, adding a little sugar, and
precipitating by solution of potassa ; a white
powder is obtained, which must be heated to
redness out of the contact of air, it is then the
substance in question. The same body may
be formed by precipitating the muriatic or

[ 368 ]

sulphuric solutions of manganese by potassa,
and treating the precipitate by heat ; the white
powder, when exposed to air, rapidly changes
its colour to yellow, then puce colour, and lastly
red brown ; to* be preserved it should be washed
in boiling water, which contains little air, and
the water driven off from it in a retort filled
with hydrogene gas.

The dark olive oxide of majtganesum in its
pure form, when examined in large quantities,
appears almost black, but when spread upon
white paper its olive tint is apparent. It takes
fire when gently heated, increases in weight,
and gains a browner tint. It slowly absorbs
oxygene from the air, even at common tempe-
ratures. It is the only known oxide of manga-
nesum which dissolves in the acids without
effervescence. The white powder produced by
the action of acids on solutions of this oxide, is
a compound of the oxide and water, or the Ivy-
drated oxide oj manganesum ; and the different
tints that it assumes by exposure to air, seem to
depend upon the formation of smaller, or larger
quantities of the dark brown oxide, which pro-
bably retains the water contained in the white
hydrat, and in this state is deep puce coloured ;
and when the water is expelled from it, it becomes
dark brown, and then appears to be the same
substance as the native oxide of manganesum,

[ 369 1

whiGh may be called the peroxide of tnanganesiim.
The specific gravity of the peroxirle is about 4 ;
it is not capable of being combined with any
of the acids ; it gives off oxygens gas by a strong
lieat, as has been already stated, and by intense
ignition it is partly or wholly converted into
the first or olive oxide of. man2;anesum- From
some experiments that I have made on the two
oxides of manganese, I conclude that the olive
oxide consists of about 2 1 of oxygene to 79 of
metal, and that the dark brown oxide contains
nearly ten per cent, more of oxygene. Accord-
ing to these estimations, supposing the olive
oxide a deutoxide, or an oxide containing two
proportions of oxygene, the number represetit-
hig manganesumwill be 113 ; and the olive oxide
will be represented by 143 ; and the dark brown
oxide by 158, that is, it must be atritoxide or an
oxide containing three proportions of oxygene.
The white hydrated oxide of manganesum ap-
pears from ray experiments to contain about
24 per cent, of water. Hence it may be re-
garded as consisting of one proportion of olive
oxide of manganesum 143, and 34 of water, and
the number representing it is 17 7. This hydrat
is erroneously described in chemical books as
the oxide of manganesum containing the
smallest (juantily of oxygene; and there are
VOL. I. B b

[3)0]

tnany other cases in which hydrats have been
confounded with oxides.

It has been supposed that there is a peculiar
oxide of manganese, which may be procured by
alkalies from the sulphuric solution; but when
this solution is concentrated the precipitate is
the pale hydrat, having a very slight tint only
of puce colour apparently from the formation
of a little of the other oxide in consequence
of the absorption of oxygene from the air dis-
solved in the alkaline solution used for its pre-
cipitation. It has been likewise conceived that
there is a green oxide of manganesum ; the
olive oxide becomes green by the action of
potassa; but in this case a combination takes
place between the alkali and the oxide. I have
made many experiments on the native dark
©xide by expositig it at different intervals for
several hours to intense heat: in these cases it
passed through different shades of brown and
olive brown, and finally became dark olive.
Colour is too indefinite a property to found a
definite species upon ; a mere change of tempera-
ture, without any evident change in composition,
alters the colours of many bodies; and it is very
probable that the different shades of colour of
different precipitates from solutions of manga-
ncsium depend upon mixtures of the white

[371]

liydrat with the puce coloured hydrat formed at
the time of precipitation by the absorption of
oxygene from the air in the fluid, and the white
hydrat seems to be always the result of the ac-
tion of alkali on solutions, in cases when there
can be no interference from the influence of
free or loosely combined oxygene,

4. A compound of chlorine and mangane-
sum may be obtained by combustion of the
metal in chlorine, or by heating strongly the
substance obtained by the solution of manganese
in muriatic acid. When made in this last way,
it appears as a pale pink coloured substance,
and semitransparent, and in brilliant scales.
This compound has been described by Mr. J.
Davy as consisting of chlorine and manganese,
and from his experiments may be considered
as consisting of one proportion of the metal 113,
and two ©f chlorine 134. It is probable that ano-
ther compound consisting of one proportion of
the metal and two of chlorine may be formed.

5. Hydrogene, azote, sulphur, and charcoal,
have no distinct chemical action on mangane-
sium,

6. Phosphorus has been combined with man-
ganesium by Pelletier ; the phosphuret is a
substance possessing metallic lustre and very
combustible; its constitution has not yet been
ascertained.

[ 372 ]

. /• The action of boron, and the metals of
the alkalies, and earths, on manganesium has
not yet been tried.

8. Mano-anesum in its oxidated form is of
considerable use in certain arts. Its application
for the production of chlorine has been already
described. It Is employed in glass-making, for
depriving glass of colour : when in its state of
full oxidation it gives a purple tint to glass,
which is destroyed by thrusting a piece of wood
into the melted glass, the inflammable matter
of which seizes upon a part of its oxygene.

It is* in some cases used to give colours to
enamels in the manufacture of porcelain. The
changes of colour of glass containing oxide of
manganesum according to its different states of
oxidation are easily exemplified by adding a
little dark oxide to powdered glass mixed with
borax, and fusing them by the blow pipe : as
long as the globule is preserved within the blue
flame, where there is combustible matter, it
remains colourless; but when it is exposed to
air at the extreme point of the flame it becomes
purple. 1 am inclined to believe that the
deutoxide is the only oxide which enters into
combination with vitrifiable substances ; and
that the peroxide when formed is mechanically
diffused through the glass, and being produced
cnly in very minute quantities is transparent

[ 373 I

and coloured. There is great reason to believe
that the colouring matters of many gems are
merely oxides finely divided in a state of me-
chanical diffusion thfOU2;h their substance,

13. Zinc or Zincum.

1. Zinc is procured for the purposes of
commerce from various ores known by the
names of calamine and blende or black jack.
To obtain the metal from calamine, which is
a combination of zinc with oxygene and car
bonic acid, the ore is strongly ignited with
charcoal or carbonaceous substances ; the zinc,
which is volatile, rises at a strong red heat, and
becomes condensed in the cool part of the
furnace or retort in which the process is carried
on. Zinc is procured from blende by a similar
operation, but the blende must be previously
roasted, that is, exposed for a long while to a
dull red heat in a state of minute division. The
zinc of commerce is. seldom quite pure; to
obtain it in this state white vitriol or sulphate
of zinc is dissolved in pure water and exposed
to the action of a plate of common zinc ; this
will separate any volatile metals that may hap-
pen to exist in the solution, which is then to
be precipitated by subcarbonate of potassa: the
white precipitate ignited with charcoal powder
affords the metal.

[ 374 ]

2. Zinc is of a bluish white colour. Its
hardness is nearly equal to that of copper. Its
specific gravity varies from 6.8 to rather more
than 7. When hammered it is 7-2. Its fusing
point is 680° Fahrenheit, at a red heat in close
vessels it volatilizes; and at this temperature in
the atiKOSphere it burns with a brilliant bluish
white flame. It has a certain degree of duc-
tility, and when heated a little above 212° Fah-
renheit, it is malleable, and when annealed it
may be passed through rollers, and obtained in
small thin sheets or leaves ; it may be drawn
into wire, the tenacity of which, according to
Muschenbroek, is such, that a wire of — of an
inch in diameter will support a weight of about
261bs. Its capacity for heat, according to
Wilcke, is 0.102.

The atmosphere has but little effect on zinc
at common temperatures ; by exposure to the air
for some time it acquires a grayish coloiar on
the surface, which is owing to a partial oxid-
ation. Zinc filings very slowly decompose
water, hydrogene gas is evolved, and oxygene
combines with the metal. The effect is rapidly
produced when steam is passed over zinc at
elevated temperatures. Zinc in thin leaves
introduced into chlorine takes fire, and burns
with a white light; even when in thick wire it
may be made to burn in this gas by a gentle heat.

[ 375

3 There is one well known combination of
zinc with oxygene ; it is obtained by the com-
bustion of zinc in the atmosphere, or by the
precipitation of solutions of zinc in acids by
alkalies and subsequent ignition. When ex-
amined in a state of minute division, such as it
appears when obtained by combustion, it is
white, and similar to cotton in its appearance ;
but when examined in mass it has a tint of pale
yellow. It becomes fluid at a white heat, and
is capable of being volatilized by an intense
white heat. It is soluble in most of the acids,
and in aqueous solutions of the fixed alkalies ;
when precipitated from its acid solutions by
alkalies, it is in the state of combination with
water, and a strong red heat is required for
the expulsion of the water with which it is
combined. From my experiments, and those
made by my brother Mr. John Davy, it appears
that the white oxide of zinc contains about 82
parts of metal and 18 of oxygene. M. Proust
eives 80 to 20, which is not a wide difference.
On the estimation of 18 per cent., supposing
that the oxide of zinc consists of one proportion
of oxygene and one of metal; the number re-
presenting zinc is 66 taking away the fractional
part; the oxide of zinc is represented by Si:
arid the hydrate, supposing it to contain one
proportion of water, will be denoted by 17

*

C 376 ]

added to 81 ; but as yet no experiments have
been made to she\y that this is the composition
of the hydrate. It has been supposed that
there is a gray oxide of zinc produced by keep-
ing zinc melted in the open air ; and a yellow
oxide formed by fusing the white povv^der pro-
duced by precipitation from acids, both con-
taining less -oxygene than the oxide just de-
scribed ; but there are no facts to warrant the
idea that these bodies are distinct compounds
of zinc and oxygene. The gray powder formed
upon the surface of melted zinc, I am inclined
to consider as a mixture of the white oxide
with small particles of unburnt zinc, and the
yellow oxide the same as tlse oxide produced
by combustion free from water.

4. When ziiic is burned in chlorine a solid
substance is formed of a whitish gray colour
and semitransparent. This is the only com-
pound known of zinc and chlorine. It may
likewise be made by heating together zinc
tilings and corrosive sublimate ; it is as soft as
wax, fuses at a temperature a little above 212\
and rises in the gaseous form at a heat much
below the red heat. Its taste is intensely acrid,
and it corrodes the skin ; it acts upon water
and dissolves in it, producing much heat, and
its solution decomposed by an alkali affords the
white hydrated oxide of zinc. The compound oC

•

[ 377 ]

2!!licand clilorine lias been caiied butter of zinc'
and muriate of zinc; following the nomenclature
already proposed us name will be zhicane; from
the experiments of my brother, Mr. John Davy
it consists of nearly equal parts by weight of
zinc and chlorine ; consequently it contains one
proportion of metal and one of gas 66 and 67,
and the number representing it will be 1 33.

5. It is not easy to combine zinc and sulphur.
"When a solution of sulphuretted hydrogene
and an alkali is dropped into an acid solution
of zinc, a whitish powder falls down, which
has been supposed to be a siilphnret of zinc.
When zinc and sulphur are heated together in
close vessels the sulphur rises in vapour with-
out uniting to the zinc; but it is stated by Mr.
E. Davy, that in some experiments made in the
laboratory of the Royal Institution, in which
sulphur in vapour was passed over melted zinc,
they united, and formed a white crystalline
substance, analogous to the substance found in
nature, and called phosphorescent blende, The
proportions of the elements in the blendes, or
supposed siilphurets of zinc, have not yet been
ascertained with accuracy; but if some experi-
ments on record can be depended upon they
must contain two proportions of metal to one
of sulphur.

6. Zinc combines with phosphorus ; when

[ 378 ]

the metal is fused and the phosphorus brought
in contact with it, The phosphoret of zinc was
discovered by Pelletier ; it is possessed of me-
tallic splendour, and is of a dull gray colour
analogous to lead ; when hammered or filed it
emits the odour of phosphorus. From expe-
riments made on its composition in the labora-
tory of the Royal Institution by Mr. E. Davy,
it is probable that it consists of one proportion
of phosphorus and one of metal.

7, Zinc has not been combined with hydro-
gene, azote or boron : zinc sometimes during its
solution in acids leaves a residuum havina: the
characters of carbonaceous matter : Imt no de-
finite compound of zinc and carbon has as yet
been described.

8, Zinc readily enters into union with the
metals of the fixed alkalies ; great heat is pro-
duced during the process, and metallic com-
pounds or alloys are obtained, which rapidly
decompose vv-ater and tarnish in the atmosphere.

9, Zinc is applied to a number of import-
ant uses : it is particularly employed in the
manufacture of brass and tombacs ; w]:ich con-
sist of this metal combined with different pro-
portions of copper. It is used by the Chinese
in various alloys : some of its combinations are
employed in medicine.

[ 379 ]

jTzw or Stannum»

1. Tin is procured from the native combi-
nations of this metal with oxygene, known by the
names of tin stones, or oxides of tin, by ignition
with charcoal or carbonaceous substances. The
metal obtained from these ores is not pure. To
obtain it in a state of purity, metallic tin should
be boiled for some time in solution of nitric acid,
the white powder formed, should be well washed
in pure water, and heated strongly in contact
with about ^ of its weight of charcoal powder
in a covered crucible for about half an hour ; a
button of pure tin will be found at the bottom
of the crucible.

2,, Tin has been known since the earliest
periods of civilization ; it was used in the time '
of Moses : it is mentioned by Homer, and was
brought from Cornwall by the Phoenicians and
Greeks, some centuries before the Christian era;
it is called by Aristotle Kacro-m^oi/ KATJxoy, or
Celtic tin. The colour of tin is white, and re-
sembles that of silver. Its hardness is greater
than that of lead, and less than that of zinc.
Its specific gravity is 7.291, and it is some-
what increased by hammering ; it is very mal^
leable, and may be extended into extremely
thin leaves. Tin foil is about the -jfo o- P*''^'^ of
an inch thick ; it has comparatively little

[ 38a 3

ductility or tenacity. It is flexible, and wlieii
bent produces a crackling noise. It has a slight
taste, and when rubbed emits a peculiar smell. It
fuses at 442 Fahrenheit, but requires an intense
degree of heat for its evaporation. Its capa-
city for heal, according to D.dtcn, is, .07. It
acquires a slight tarnish by exposure to the
atmosphere, but undergoes no further change.
It is not affected by water at common tempe-
ratures, but when steam is passed over red hot
tin it is decomposed, oxide of tin is formed, and
hydrogene gas is evolved. When heated
strongly jn air, it takes fire and burns with a
pale white light ; when burnt upon charcoal
by a stream of oxygene gas, the colour of the
flame is white, edged with violet. Tin foil
burns when very gently heated in chlorine.

3. There are two definite combinations of tin
and oxygene: the first, which maybe called the
proloxide, is gray ; the second, which may be
called the per oxide^ is white; the first is formed
by heating tin in the air, or by dissolving tin in
muriatic acid, and precipitating the solution
whilst recent, and before it has been exposed to
air by solution of hydrat of potassa, not added
in excess. This substance, after being heated
to whiteness, is the protoxide of tin ; and it is
converted into the peroxide by being boiled
with diluted nitric acid, dried by evaporation"

[381]

and heated to redness. From experiments which
i have mac^e, it appears that the protoxide of
tin contains about 13.5 per cent, of oxygene,
and from experiments made hy Mr. John Davy,
the peroxide is composed of about 24 of oxygene
and 76 of metal. These oxides are difficultly
fusible bodies, insoluble in water, soluble in
diluted oil of vitriol, and in fixed alkaline solu-
tions. Computing from their composition, and
supposing one to consist of one proportion of
tin and one of oxygene, and the other of one of
tin and two of oxygeoi", the number represent-
ing tin will be 110, and the number standing
for the protoxide will be 125, and that standing
for the deutoxide, or white oxide, 140. Both
these oxides appear capable of combining with
water to form hydrats ; and when precipitated
from their acid solutions , they always con-
tain water, but experiments are wanting (^o
determine the quantity: both are insoluble
in water.

4. As there are two combinations of tin with
oxygene, so there are two which it forms with
chlorine. When tin is burnt in chlorine a very
volatile clear liquor is formed, a nonconductor
of electricity, and which, when mixed with a
little water, becomes a solid crystalline sub-
stance, a true muriate of tin containing the
jperoxide of tin. This liquor, which h^s

[ 382 ]

been called Libavias's liquor, from its dis-
coverer Libavius, may be likewise procured by
heating togetiier tin filings and corrosive subli-
mate, or an amalgam of tin and corrosive subli-
mate. It consists, according to the analysis of
Mr. J. Davy, of two proportions of chlorine
134, and one of tin 110; and according to the
proposed principles of nomenclature, its name
will be stamianea. The other compound of tin
and chlorine is a gray semitransparent crystal-
line solid ; it may be procured by heating toge-
ther an amalgam of tin and calomel ; it dissolves
in water and forms a solution which rapidly
absorbs oxygene from the air, depositing oxide
of tin. This compound of chlorine and stan-
nane, it appears from the experiments of Mr.
J. Davy, who first described it, consists of one
proportion of tin 110, and one of chlorine 67 ;
it may be called stannane,

5. There are two siilphurets of tirij one may
be made by fusing tin and sulphur together ; it
is of a blueish colour and lamellated structure ;
and from the experiments of my brother con-
sists of one proportion of tin and one of sul-
phur 110 and 30, The other sulphuret of tin,
or the supersulphuret, is made by heating to-
gether the peroxide of tin and sulphur ; it is
of a beautiful gold colour, and appears in fine
flakes ; it was formerly called aurum musivum.

[ 383 ]

It has been supposed by Pelletier and Proust
to contain tin in an oxidated state, but Mr. John
Davy has shewn that this is not the case ; and
that it consists merely of one proportion of
metallic tin combined with two proportions of
sulphur, 110 and 6o ; so that the number re-
presenting it is 170.

6. Tin combines with phosphorus when the
two substances are heated together. As yet
only one compound is known, which appears
from my experiments to consist of 17 per cent,
of phosphorus, and therefore may be regarded
as composed of one proportion of tin and one
of phosphorus, 1 10 and 20. The phosphoret of
tin has a metallic appearance, is so soft that it
may be cut with a knife ; the phosphorus burns
when it is gently heated in the air.

7. Tin has not been combined with hydro-
gene, azote, carbon, or boron ; it readily unites
to the metals of the fixed alkalies, and forms
alloys which speedily tarnish in the air, and
which effervesce in water. It unites with zinc
by fusion ; the alloy is harder than zinc and
stronger than tin.

8. Tin is a metal of great use, and of various
application ; it is an important ingredient in
pewter, bell-metal, and bronze ; it is employed
to cover culinary vessels, as tin plate ; some of
its acid compounds are used in dyeing. Tin is

[ 384 ]

almost always found in nature in the oxidated
state, and in the crystalline form ; and it appears
from the analysis of Klaproth that the native
oxide or tin stone of Cornwall must contain one
proportion of tin and two of oxygene. All the
well known combinations of this metal are such
as they ought to be according to the theory of
definite proportions, and its compounds with
oxygene, sulphur, and chlorine, afford similar
results, which correspond with the numbers
gained from its simplest combination.

16. Iron or Fcrrum.

1. The iron of comtaerce is obtained froixi
various ores of that metal, in which it exists
combined with oxygene, by intense ignition
with carbonaceous substances : the purest iron
is made from an ore called haematites by igni-
tion with charcoal ; and the metai is hammered
whilst in a softstate, exposed to air.tillitbecomes
ductile. Iron was known in the time of Moses,
and used for the manufacture of swords, knives,
and axes. It is referred to in the Iliad and the
Odyssey of Homer, A ball of iron was one of
the prizes offered by Achilles at the funeral
rites of Patroclus ; and the effect of the burn-
ing brand thrust by Ulysses and his companions
into the eye of Polyphemus, is compared by
the poet to that of the hot iron plunged int<?

[ 385 ]

watet bythe sinith. T{iie soft iron employed in
the useful arts is free from any alloy, and there-
fore maybe used for the purposes of chemistry.

S. The colour of iron is well known, and its
oilier sensible properties ; its specific gravity is
about 7.7. Its malleability, though considerable,
is inferior to that of gold, silver, and coppei'.
Its ductility and tenacity are, however, greater;
it may be drawn into extremely fme wire, and a
wire of 0.078 of an inch in diameter is capable
of supporting 549.2<5lbs. It requires the highest
heat of a wind furnace for its perfect fusion : it
is attracted by the magnet and is capable of ac-
quiring magnetism, though in its unalloyed state
it retains it only for a very short time. When
itbh is exposed to the atmosphere it slowly
combines with oxygene and carbonic acid, and
its suirface becomes covered with a yellowish
substance well known by the name of rust. It
burns with great splendour in oxygene gas, as
has been stated page At common tempera--
tures it slowly decomposes water. Hydrogene
gas is evolved, and oxygene combines with the
metal. The effect is rapidly produced when the
vapour 6f water is passed over red hot iron.
When gently heated in chlorine it takes fire
and burns with a deep red light.

3. The combinations of iron and oxygene
have been referred to, page 110. The black

VOL, I, C c

[ 386 ]

and the red-brown oxides are the only oxides of
this metal known j these substances, which have
been considered as green and white oxides, are
in fact hydrated oxides. The black oxide of
iron, which may be regarded as a deutoxide,
as containing two proportions of oxygene, is
formed by the rapid combustion of iron in
oxygene. The red-brown oxide, which must
be considered as a tritoxide, may be produced
from the black by keeping its powder red hot
for a considerable time in contact with the at-
mosphere often changing the surface. Reason-
ing on the composition of these oxides, 103
must be the number representing iron; and the
black oxide, or the deutoxide, consists of one
proportion of iron 103, and two of oxygene 30;
and the brown-red oxide, or tritoxide of 103
metal, and 4-5 oxygene. Both these oxides are
soluble in the common acids. The black pro-
duces pale green solutions ; the brown-red, deep
yellow solutions : the solutions of triple prussiate
of potassa, precipitate the solutions of the black
oxide white ; those of the red bright blue.
When solutions of these oxides are acted upon
by solutions of pure alkalies, a white precipi-
tate, having a tint of green or olive, is thrown
down from the solution containing the black
oxide ; and an orange coloured precipitate from
the solution containing the red-brown oxide ; and

[ 387 ]

both these precipitates, I find, are the oxides
combined with water or hydrates. The pale
hydrate, when exposed to air, rapidly changes
in colour, first becomes pale olive, then dark
olive, then olive brown, and last of all orange j
so that there is strong reason to conclude that
the colours of different precipitates depend upon
their being composed of mixtures of the two hy-
drates ; and solutions of the black oxide cannot
be exposed to air for a moment without being
changed by the absorption of oxygene. I have
made no experiments to ascertain the composi-
tion of the two hydrates; probably the white
contains two proportions of water. It would
seem from the experiments of Dr. Thomson
that there is a black hydrate formed by passing
steam over iron ; and which probably consists of
one proportion of iron, two of oxygene, and one
of water. Mr. Daubuisson has described a na-
tive hydrated oxide of iron.

4. There are two compounds of iron and
chlorine. The one containing tlTe largest pro-
portion of chlorine is formed by burning iron
wire in the gas. It is a very beautiful substance
of a bright yellowish brown colour. It has a high
degree of splendour, and is very volatile, rising
in the gaseous state at a temperature a little above
that of boiling water, and crystallizing in small
irrideseeiit plates. It acts with violence upon

C c 2

[ 388 ]

water, arid forms a solution of red muriate of
iron. I have called it ferranea, and I find by
analysis that it consists of one proportion of
iron 103, and three proportions of chlorine
1201.

The other compound of chlorine and iron has
been formed and analyzed by my brother, Mr.
John Davy ; it contains proportions which agree
nearly with one of iron 103, and two of chlorine
134. It is a dark gray opaque substance, fusiblfe
at d. red heat, and not rising in vapour at the
point of fusion of glass. It forms a solution of
green muriate of iron by its action upon water ,
it may be named ferrane.

5. No Combinations of iron with bydrogene
or azote are known j but this metal readily
combines with sulphur. There are two well
known sulphurets of iron; one is formed by
heating iron filings and sulphur together out
of the contact of air ; they combine with great
energy, producing the effect of ignition. The
siilphuret of iron formed in this way<is of metallic
splendour, and a dull yellow colour. This com-
pound is found in nature, and has been analyzed
by Mr. Hatchett. It is magnetie, and has beers
called magnetic pyrites. The other sulphuret
of iron, which may be called the siipersulpku7^ei,
has not yet been made artificially, but it is
found abundantly in metallic veins : it is of a

[ 389 1

bright yellow colour, and often crystallized in
cubes. According to Hatcliett and Proust, the
sulphuret of iron consists of about 63 of iron to
37 sulphur, and the supersulphuret of about 46
to 54 ; so that the quantity of iron remaining
the same, the last sulphuret contains nearly
double as much sulphur as the first; and iroa
being represented by 103^ the proportions are
not verj^ remote from two of sulphur 60 in the
sulphuret, and four of sulphur 120 in the hy-
persulphuret.

6. Iron is capable of combining with phos-
phorus ; but the proportions of the elements of
phosphoret of iron have not been ascertained j
nor is it known whether more than one com-
pound of this kind exists. The phosphoret
may be made by passing phosphorus in vapour
over ignited iron. It is very brittle, of a dark
steel gray colour, and of the specific gravity of
6.7. This substance, which was first found
in the peculiar iron called cold short iron,
because it is brittle when cold, was once sup-
posed by Bergman and Meyer to be a peculiar
metal; but Klaproth discovered its real nature.
It may be formed hkewise by heating together
phosphoric acid, iron, and charcoal.

7. Iron is capable of combining with car*
bon; and steel, perhaps the most important sub-
stance employed in the useful arts, is one of

Cc3

[ 390 ]

the results of their combination. Steel is usually
made by a process called cementation, which
consists in keeping bars of iron in contact with
powdered charcoal in a state of ignition for teq
or twelve days, in earthen troughs, or crucibles,
the mouths of which are closed with clay.
Cemented steel is made into the substance
caWed cast steel by being fused in a close crucible
with a mixture of powdered glass and charcoal.
Steel is possessed of the power of receiving
very different degrees of hardness by different
applications of heat or cold. When it is heated
to redness, and suffered to cool slowly, it is
found very soft j but if plunged into cold mer-
cury or water, it acquires extreme hardness;
and by heating hard steel to different degrees,
■it receives different degrees of temper from
that which renders it proper for files, to that
which fits it for watch springs. In the process
of tempering, the steel changes colour even
though plunged under oil. Between 430° and
450° Fahrenheit, according to Mr. Stoddart, it
assumes ^ pale yellowish tinge; at 460° the
colour is a straw yellow, and the metal is of the
temper necessary for pen knives, razors, and
fine edged tools. The colour gradually deepens
as the temperature rises higher, and it passes
through brown, red, and purple, to 580, when
it becomes of an uniform deep blue. These

[ S91 ]

changes of colour seem to depend upon some
change in the arrangement of the exterior layer
of particles of the metal ; they cannot depend
on oxidation, as they take place under mercury.
Steel is of greater specific gravity than iron ;
when the metal is hammered it is about "].$.
When it is acted upon by an acid, such as
diluted nitric acid, a black spot appears upon
it from the separation of the carbonaceous mat-
ter. Steel is attracted by the magnet, and is
capable of receiving permanent magnetism. It
is not easy to determine the exact quantity of
carbon in steel, but it consists of several pro-
portions of iron to one of carbonaceous matter.
Different specimens of steel are said, on the
authority of Bergman, Vauquelin, and Mushet,
to contain only from yto- to oi' carbon.

Iron has been converted into steel by ce-i
mentation with diamond by Morveau and Sir
George Mackenzie,

Plumbago, or blacli lead, as has been mentioned
page 313, is a compound of carbon, with -Jg- its
weight of iron. There is a substance formed
in iron founderies called kish, of a brilliant ap-
pearance, usually in thin scales, analogous to
plates of polished steel. It consists chiefly of
carbonaceous matter united to iron, and a little
manoranesum.

8. When iron and charcoal are sirongly

I 392 ]

Ignited with boracic. acid, the iron produces,
daring its solution, boracic acid, as M. Descotils
has shewn. Hence it is probable, as M. M.
Gay Lussac and Thenard have supposed, that
iron is capable of combining with boron,

9. Iron is capable of combining with potas-
sium and sodium ; these alloys are more fusible
and whiter than iron, and effervesce copiously
in water. There is great reason to believe that
alloys may be formed of iron and the metals of
the earths. Cast iron, which is produced by
fusing iron ores with pitcoal, during its con-
version into malleable iron, aifords about one
fourth of its weight of a glass, which consists of
silex, alumine, lime, oxide of iron, and oxide
of manganesum. In the process for reducing
cast iron into malleable iron called bloominz^
the iron, after being fused in a forge by a fire
of charcoal, is hammered, whilst in a soft state,
on an anvil by a large hammer worked by
water ; a vivid combustion, which seems to be
connected with the formation of the slass and
the oxides, takes place on the surface of the
mass : that the earths are formed by the oxida-
tion of metals combined in the cast iron seems
probable from the circumstance of the combus-
tion ; and the idea is confirmed by the distinct
metallic character of cast iron; it is white, crys-
tallized, and has all the appearances of a perfect

[ 393 ]

alloy. Specimens of cast iron ustially contaia
likewise sulphur and carbon.

10. Manganesum forais very readily binary
combinations with iron; the alloys have a white
colour, and are very brittle. Iron likewise
combines with tin. By fusing the two metals
together Bergman obtained two alloys; the first
containing 21 parts of tin, and one part of iron:
the second two parts of iron and one of tin.
The first was very malleable, harder than tin,
and not so brilliant; the second scarcely malle-
able and very hard. The formation of tin plate
depends upon the chemical attraction between
the two metals. Tin plate is formed by dipping
thin plates of iron into melted tin, the iron must
be very clean. It is usual to add ^ of copper
to the tin to prevent it from forming too thick
a coat.

11. To describe the uses of iron would re-
quire volumes ; as it is the most generally dif-
fused metal, so it is likewise the most important
in its applications to the purposes of society.
By means of it the earth has been cultivated
and subdued. Without iron, houses cities and
ships, could not be built. It is subservient
both to the common and the refined arts;
it forms the machinery by which the most
important mechanical powers are generated
and applied. Its uses have awakened human

[ S94 ]

industry, and made it more efficacious, and have
offered an infinite variety of resources to in-
genuity and talent.

1 7. Lead or Plumbum.

1. The lead of commerce is chiefly procured
from certain ores in which it is combined with
sulphur. The sulphur is expelled or burnt by
a long continued heat in a reverberatory furnace,
and the metal is obtained by fusion. To pro-
cure pure lead a solution of the lead of com*
merce in nitric acid, largely diluted with vi-ater^
j-nay be precipitated by zinc ; or a solution of
acetite of lead, i. e sugar of lead, may be used.
The arborescent brilhant metallic substance pro-
duced from solution of sugar of lead by zinc is
generally pure lead.

2. Lead was known in a very early age of
the world. It is often mentioned by Moses;
and is described by Homer as in common use
lit the period of the Trojan war.

Lead is of a blueish white colour, but soon
tarnishes by exposure to the air. It is the softest
0f the common metals. Its specific gravity is
11. 35^, and is not increased by hammering. It
is very malleable, but not very ductile. Its
tenacity is such that a wire of -^i.-r ^'^^^''^
in diameter, supports only ]8.4 pounds. Its
point of fusion is CIS*, but an intense degree

[ S95 3

oFheat is required for its evaporation. It com-
bines with oxygene slowly, at the temperature
of its fusion, and burns when strongly ignited
in the atmosphere; when a current of oxygene
gas is thrown upon it in this state, the flame it
emits is of a brilliant whiteness, and it sends cfF
a dense smoke. When heated in chlorine it
unites to it, but does not inflame.

3. Lead combines with oxygene in different
|3roportions ; and three of its combinations with
this substance appear to be well defined and
distinct bodies. Two of the oxides of lead may
be formed by heat with accession of air; the
one is massicot^ the other is minium, or red lead.
When lead is heated in contact with the at-
mosphere, it soon becomes of a dirty yellow,
or yellowish green colour, and at length of a
pure yellow colour. This oxide is massicot,
and is the oxide existing in the different salts of
lead ; when precipitated from these salts by
{Caustic alkalies, it falls down in combinatior^
with water, and appears as a white hj-drated
oxide of lead; the water may be expelled from
it by a strong red heat- From the experiments
of Vauquelin and Klaproth, it may be con-
cluded that this oxide of lead contains about
7 per cent, of oxygene. Litharge is this
oxide of lead, according to Dr. Thomson,
fnixed with a little carbonate of lead : litharge

[ 396 ]

is formed dormg the extraction of silver from
lead by the calcination of the lead, and the
carbonic acid is acquired from the carbonaceous
matter burnt in the flame of the furjnace.

Massicot is fusible at a strong red heat, and
appears, when fused, as a yellow glass, insoluble
in water, without taste or smell, and of great
specific gravity.

The first oxide of lead by being heated
moderately in contact with air, for a considera-
Me time, combines with an additional quantity
of oxygene, and then becomes of a beautiful
red colour, in which state it is called minium,
or red lead, 100 parts of lead carefully and
slowly converted into minium become between
J JO and 111 parts ; so that there is strong reason
to believe that the quantity of lead being the
same, the oxygene in minium is to that in mas-
sicot, as 3 to 2. Minium exposed to a strong
red heat gives olf from 3 to 4 per cent, of oxy-
geiie gas, and becomes massicot.

When nitric acid is digested upon minium, a
part is dissolved, but a puce coloured powder
remains, which contains more oxygene than
minium, and the formation of which seems to
be owino; to the circumstance that the oxide,
which dissolves during its solution, becomes
massicot, and affords oxygene to the undissolved
portion, so as to convert it into a new substance.

I S97 ]

The puce coloured oxide of lead, long dried
at 212°, loses from 6 to 7 parts per cent, dur-
ing its conversion into massicot by fusion; so
that it may be considered as containing twice
as much oxygene as that oxide, the proportion
of lead being; considered as the same. On these
views massicot will be a deutoxide of lead,
minium a tritoxide, and the puce coloured
oxide a tetroxide ; and the number represent-
ing lead will be 398 ; and the oxides will be
composed respectively of 398 of metal, and 30^
45j and 60, of oxygene,

4. One combination only of lead with chlorine
is known, it may be obtained directly by heating
lead in chlorine, or by decomposing the oxides
of lead by chlorine, in which case oxygene is
expelled, or by acting on oxides of lead by
muriatic acid gas, when water is formed. The
combination of chlorine and lead is a dull
whitish seihttransparent substance, fusible at a
heat below redness, and volatile at an interne
heat. This substance has a sweetish taste,
and is soluble in parts of cold water. It
was called horn lead by the old chemists,
and improperly muriate of lead by modem
chemists. The name proposed for it is plum^
bane. According to my experiments made oa
the absorption of chlorine by lead, it contains
401 of lead to 131 of chlorine, which ag-reei

t 398 ]

Very nearly indeed with one proportion of metal^
and two of chlorine; and this compound de*>
composed byalkah'es affords the oxide contain-'
ing two proportions of oXygene.

5. Sulphur is easily made to unite With lead
by a gentle heat. One combination only of
these bodies is certainly known, and it is the
same as the substance found in nature, referred
to in the beginning of this sectioiij and called
galena. It is very brittle, brilliant, and of a deep
blueish gray colour. It is less fusible than lead,
and crystallizes in cubes. 100 parts of lead in
becoming the sulphuret unite to about 15 parts
of sulphur; which gives the sulphuret, as con*
sisting of one proportion of metal and two prof
portions of sulphur.

6. A compound of lead with phosphorus
may be formed by fusing together equal parts
of filings of lead and phosphoric acid. It is of
a silver white colour with a shade of blue ; may
be cut with a knife, but is brittle under the
hammer. The same substance may be formed
by bringing phosphorus in contact with melted
lead. According to Pelletier it consists of 8S
parts lead and 12 of phosphorus, which gives
nearly 3 proportions of phosphorus 6o, to one
ofleadsgS.

7. There are no known combinations of lead
with hydrogene, azote, carbon, or boron.

[ 399 3

8. Lead unites by fusion with tli6 metals df
the fixed alkalies, and Form compounds which
tarnish in the air, and are readHy decomposed
by the agency of water.

9. Lead combines with zinc, tin, and iron.
Its alloy with iron is made with great difficulty,
and has not been accurately examined. The
alloys of zinc and lead may be easily made by
fusion. These alloys are harder than zinc, and
ductile. In whatever proportions the metals
are melted together, the mass, on cooling, is
found to contain them in a state of chemical
union or intimate mixture. Lead and tin com-
bine in a similar manner ; this alloy is harder
and more tenacious than tin. It is said by
Muschenbroeck that these qualities exist in the
highest degree in the alloy, when it is composed
of 5 parts of tin, and one of lead; which quan-
tities nearly correspond with single proportions
©f each of the two metals. This mixture is
often employed to cover copper vessels ; and,
as appears from the experiments of M. Proust,
is difficultly acted upon by vegetable acids, and
when acted upon, the tin is dissolved, and not
the lead ; so that such vessels may be safely
employed for culinary purposes.

30. Lead is very extensively used both in
thte common and refined arts. Its oxides, and
some of its saline combinations, are extensively

[ 400 ]

applied in painting; white lead is the deutoxide
combined with carbonic acid. Both massicot
and minium are common pigments. Thedeut-
oxide combined with chromic acid forms the
most beautiful and permanent deep yellow
known. Lead is used as an ingredient in
various solders; it is applied for covering
houses and churches. It will he unnecessary
to dwell upon its still more familiar applica-
tions. Its oxide forms an important part of flint
glass, and is used in various enamels and pastes.

18. Antimoivy or Anthnonium.
The ancients were acquainted with certain
ores of antimony ; the most common of them,
the sulphuret of antimony, was employed by

the ladies of the oriental countries to tino^e the

o

extremity of the eyelid black for the purpose
of giving greater brilliancy of eflect to the pupil,
Basil Valentine is the first chemist who has de-
scribed the process of extracting antimony from
the sulphuret, though it does not appear that
he was the inventor of this process. He pub-
lished his Currus Triumphalis Antimonii to-
wards the end of the fifteenth century*

To procure antimony, the common antimony
sold by druggists, which appears as a series of
crystals, like needles, possessing the metallic
brilliancy, and which are composed of the metal

C 401 ]

and sulphur, are ignited with half their weight
©f iron filings, and a quarter of their weight of
nitre added when they arp in fusion ; the anti-
mony will be found in the bottom of the vessvd
in which the experiment is made. To obtain
it quite pure, it may be dissolved in aqua regia,
water is added to the solution, a white powder
will fall down ; this is to be ignited for about
BO minutes, with twice its weight of tartar, when
the metal will be produced.

2. Antimony is of a brilliant white colour
with a shade of blue, its hardness is equal to
that of zinc. Its specific gravity is about 6.8.
It is very brittle, and may be easily pulverised.
It has little tenacity. It fuses at about 810**
Fahrenheit. On cooling it crystallizes, and its
laminated structure is owing to the new arrange-
ment of its parts. It is but little afiected by
exposure to the air or water at common tem-
|)eratures ; but when the vapour of water is
passed over red hot antimony, it acts so power-
fully upon the water, as to decompose it with
explosions.

3. Two combinations of antimony with oxy-
gens are known ; one, the fusible cvide, is ob-
tained by dissolving antimony in muriatic acid
by heat, and adding w^ater to the concentrated
soluiion, a white powder falls down, which,

VOL. I. D

[ 402 ]

when washed with a solution of subcarbon^ite
of potassa, and afterwards with distilled water,
is a combination of the fusible oxide with water,
and by fusion at a red heat it becomes the pure
oxide. This substance is of a dirty yellowish
white colour. It crystallizes by slow cooling
after fusion. By being strongly heated in con-
tact with the atmosphere it combines with more
oxygcne, rises in the volatile form, and con-
denses in white crystals of a silvery lustre ; and
this substance is the peroxide or antimony satu-
rated with oxygene. This oxide is much less
fusible, yet more volatile than the other, and is
more difficultly combined with acids. The
fusible oxide, in its combination with water,
was for a long while called the powder of
Algaroth, from its discoverer Algarotti. Anti-
mony burns, when heated strongly in the air,
with a faint white light, and produces the
second or the volatile oxide, which rises from
it in the form of a dense white smoke. From
experiments made on these two oxides by Mr.
John Davy and myself, it appears that the fusible
oxide contains -f- as much oxygene as the volatile
oxide, supposing the metal to be the same in
both ; and calculating from his experiments on
the fusible oxide, thenumber representing anti-
mony is 1 7 Oj the fusible oxide may be considered

t ]

as consisting of 170 metal^ and 30 of oxy-
gene, an J the peroxide of I70 metal, and 45
bxygene.

4. Antimony burns spontaneously when
powdered and thrown into chlorine. In this
"way the only known compound of antimony
and chlorine, antimonane, or butter of antimony,
is formed. It is a soft semitransparent substance,
of a yellowish white colour, very fusible, vola-
tile at a moderate decree of heat. It crystallizes
in parallelopipeds. It is a very caustic and cor-
rosive substance ; it acts with great energy upon
water: with a small quantity of water it heats
"violently, and forms a solution ; a large quantity
precipitates the fusible oxide of antimony, and
muriatic acid is found in the solution. Anti-
monane may be likewise formed by the distilla-
tion of a mixture of powdered corrosive subli-
mate and antimony. From the experiments
of Mr. John Davy, it appears to contain 44
per cent, of chlorine, and therefore may be
regarded as consisting of one proportion of
metal and two of chlorine.

5. Sulphur and antimony are readily com-
bined by fusing them together, when they form
a compound of metallic appearance, similar to
the natural sulphuret, and which is much more
fusible than antimony: according to Proust it
contains about 25 per cent, of sulphur, and

[ 404 ]

may therefore be considered as consisting of
one proportion of metal, and two proportions of
sulphur, 170 and 60.

6. Antimony has not yet been combined with
hydi'ogene, azote, carbon, or boron.

7. Antimony combines with phosphorus by
fusion. According to the experiments of M.
Pelletier, the phosphuret is white, brittle, and
has the metallic lustre; its composition has not
been determined.

8. Potassium and sodium may be combined
with antimony by fusion ; they form alloys
very similar to those they form with lead and
tin in their obvious properties. Antimony
may be combined with all the other metals
which have been described. The alloy of tin
and antimony is employed in the arts, particu-
larly for making rnusic plates. Antimony very
much impairs the magnetic properties of iron.
The alloy of lead and antimony is used fo-r
printers types ; and for this purpose it is formed
of 16 pgfrts of lead and one of antimony. The
oxides of antimony are used for giving a yellow
colour to glass. Various combinations of anti-
mony are employed in medicine.

19. Bismuth or Bismiithiim.

1. The bismuth of commerce is procured
from ores which usually contain it in the metallis

[ 405 ]

state, or combined with sulphur, by roasting,
and ignition with charcoal. The metal may-
be obtained in a state of purity by dissoi%'inT
the ore in strong nitric acid, and adding water
to the solution, a white precipitate will appear,
it is to be washed, dried, and heated to a dull
red for about 20 minutes, with a little oil, and
some black flux, a substance made by heating
together nitre and tartar ; a globule of metal
will thus be procured.

2. The ores of bismuth were first described
by Agricola before 1530; the properties of the
pure metal were not known before the middle
of the last century. The colour of bismuth is
white with a slight tint of red. It is nearly of
the same hardness as copper. Its specific gra-
vity is 9.822, and it is increased by hammering.
It is brittle, it cannot be drawn into wire. Its
tenacity is such that a rod ~ of an inch in dia-
meter sustains a weight of about 29lbs. It
fuses at about 476° Fahrenheit, and if slowly
cooled crystallizes in cubes: if it is exposed to
a strong heat in close vessels it sublimes un-
altered. Bismuth acquires a superficial tarnish
by exposure to the air; it is not affected by
water.

3. One combination only of bismuth and oxy-
gene is certainly known. When bismuth is kept
at a dull red heat in open vessels, its surface

[ 406 ]

soon becomes tarnished ; and by exposing fi esk
surfaces the whole may be converted into an ox-
ide. When heated more intensely in the atmos-
phere, or in oxygene gas, it burns >yith ablueisb
flame, and a yellow oxide is formed, which fusea
at an elevated temperature. The oxides formed by
slow or rapid combustion are of the same kind.
When in powder, they are yellow, when fused,
>they form a yellowish green vitreous mass. The.
oxide of bismuth requires an intense degree of
heat for its volatilization. When this oxide
is precipitated from its solutions in adds by^
water or alkalies, it appears as a white powder,
which probably is a compound of the oxide and
water. Klaproth has shewn that 100 parts of
bismuth by treatment with nitric acid and water,
produce about 123 parts of the white powder.
This powder has been called mapistery of bis-
muth. Geoffioy found 100 parts of bismuth
become 110 parts by exposure to heat and air ;
but in his experiments probably some of the
metal escaped oxidation. Mr. J. Davy has found,
the yellow oxide to contain in 100 parts 90,
parts of metal, and 10 of oxygene, and this
estimation is very near that of Bucholz; and!
supposing the oxide to consist of one propor*
tion of metal, and one of oxygene, the number
representing bismuth will be 135.

4' JBismuth, when thrown in fine powdej

[ 407 ]

into chlorine, takes fire, and burns with a pale
blue light; in this case the only known com-
pound, bismuth and chlorine, is formed. It
has been called hutter of bismuth. It may be
called bismuthane. It is an easily fusible sub-
stance, volatile at a moderate heat ; its colour is
grayish. It corrodes the skin, and is readily
decomposed by water ; the bismuth combines
with the oxygene of the water; the chlorine
with its hydrogene. From the experiments
of Mr. J. Davy, it appears that bismuthane
contains 33.6 per cent, of chlorine, and there-
fore may be considered as consisting of one
proportion of metal, and one of the gas, 135
and 67.

5. There are no known combinations of bis-
muth with hydrogene, azote, carbon, or boron.

6. Bismuth combines with sulphur when
they are fused together; the sulphuret is of a
bluish gray colour, and has metallic lustre.
According to Mr. J. Davy's experiments it con-
tains about 18 per cent, of sulphur. By this
estimation, the sulphuret of bismuth must con-
tain about one proportion of metal to one of
sulphur.

7. Bismuth appears to have little affinity for
phosphorus, the attempts hitherto made to form
this compound have been unsuccessful.

8. The action of the metals of the fixed

[ 408 ]

alkalies on bismuth is similar to thai which they
exert on other easily fusible metals.

9. Ei&muth forms alloys \*iih all the metals
which have been descnbed, except zinc ; these
alloys have been little examined. It sometimes
enters into the composition of pewter ; and it
forirxS a principal pare of Newton's fusible metal.
This alloy is composed of 8 parts of bismuth,
5 of lead, and 3 of tin,, and melts at a tempera-
tare below that at which water boils.

10. Bismuth is not of much use in the arts.
The white hydrat is employed as a pigment,
but is not very permanent, becoming yellow by
the action of light. It is probable that the
Roman ladies used the oxide of bismuth for
whitening the skin ; for Martial in speaicing of
a lady, who made too free a use of cosmetics^
describes her as afraid of the sun.

This metal is sometimes employed in .illoys
to make easily fusible solders. The white hy-
drat has been lately employed in medicine, as a
remedy in spasmodic affections of the stomach,

20. Tellurium,
1. Tellurium was discovered by Klaproth, in
179S, and was procured by him from an ore
found near Zalethna in Transylvania, in which
it exists, in alloy with gold, lead, and silver.
The process for obtaining the metal is very

[ 409 ]

simple; the ore is dissolved in aqua regia made
of a mixture of 1 part strong nitric acid and
two parts raurlatic acid. Wiien the solution is
saturated, water is to be added, a white powder
falls down, which, when dried, and heal ed in a
retort of glass, with of its weight of charcoal
powder, will afford pure tellurium,

2. Tellurium is of a colour nearly the same
as that of antimony. It easily fuses, and rises
in vapour at a strong red heat. It burns, when
heated in the air, with a vivid biueish green
flame, sending off a dense while smoke. Its
powder takes fire in chlorine. Its specific gra*
vity is 6.1 15,

3. One oxide of tellurium only is known, the
substance formed by combustion of the metal ; it
is white with a tint of yellow, when examined in
the mass. It fuses by a strong heat, and requires
a very high temperature for its volatilization.
When precipitated from its acid solutions, it is
found in union with water, as a white hydrat.
According to Klaproth 178 grains of oxide of
tellurium afford I48 grains of metal: supposing
the oxide to consist of one proportion of oxy-
gene, and one of metal, the number represent-
ing tellurium will be 74.

4. When tellurium is burnt in chlorine an
easily fusible substance is formed, which rises
jn vapour at a strong heat, and crystallizes. Its

[ 410 J

colour is white: it is seraitransparent ; when
decomposed by water, it affords the white hy-
drated oxide. From my own experiments it
appears this compound, or tellurane, consists of
2 in weight of metal to I.83 of chlorine; ife
may therefore be regarded as composed of one
proportion of metal 74, and of chlorine 67.

5. Tellurium and hydrogene are capable of
being combined. To make this combination,
hydrat of potassa and oxide of tellurium are
ignited with charcoal, and the mixture acted
upon, by diluted sulphuric acid, in a retort con-
nected with a mercurial pneumatic apparatus ;
an elastic fluid will be generated, which consists
of hydrogene holding tellurium in solution.
It is possessed of very singular properties. It
is soluble in water, and forms a claret coloured
solution. It combines with the alkalies. It
burns with a blueish flame, depositing oxide of
tellurium. Its smell is very strong and pecu-
liar, not unlike that of sulphuretted hydrogene.
I discovered this elastic fluid in August 1809,
When tellurium is made the electrical negative
surface in water in the Voltaic circuit, a brown
powder is formed, which appears to be a solid
combination of hydrogene and tellurium, and
■which was first observed by M. Ritter, in I8O8 :
a claret coloured solution of the gas is likewise
formed when the water is free from air. The^

[ 411 ]

<;omposition of telluretted h/drogene gas, and of
the solid k^druret of tellurium has not been,
yet ascertained.

6. Tellurium has not been combined with
azote, carbon, or boron. No experiments are
on record as to its action on phosphorus.

7. It unites to nearly its own weight of sul-
phur by fusion ; the result is a lead coloured
striated mass. It seems probable that the sul-
phuret contains two proportions of sulphur.

8. Very few experiments have been made
upon the alloys of tellurium. It combines
readily by fusion with potassium and sodium,
producing heat and light; and forms with them
difficultly fusible alloys, which, when thrown
into water, produce purple solutions consisting
of the alkalies united to telluretted hydrogene.

Tellurium has as yet been found in quantities
too small to render it applicable to any of the
purposes of the common arts.

21. Cobalt or Cobaltum.

1. Cobalt is procured from its ores, which
are for the most part combinations of this sub-
stance with other metals ; or of its oxide with
arsenic or sulphuric acids. It is difficult to
obtain the metal in a state of complete purity.
The pure oxide may be procured by dissolving

[ 412 1

the ore known hy the name of arsenical coball in
nitric acid. The sulphur either remains on
the surface, or is acidified with the arsenic, when
both are to fee separated by nitrate of lead.
The excess of lead is to be removed by a little
sulphuric a-cid, and the copper, if any, preci-
pitated, by a bar of iron. The clear solution
is to be precipitated by carbonate of potassa,
and the precipitate digested with solution of
ammonia. The ammoniuret is to be evaporated
till it does not tinge turmeric, and then acted
on by solution of potassa : the precipitate, if
any, is to be separated, and the clear fluid eva-
porated to dryness. The solid matter obtained
by evaporation will afford cobalt when mixed
with a little very fine charcoal powder, and
exposed to an intense heat for about half an
hour in a covered Hessian crucible.

Metallic cobalt was first procured by Brandt
in 1733.

gray colour, with a
tint of red ; its hardness appears to be greater
than that of copper ; its specific gravity is about
7.7. It is rather brittle ; its fusing point is very
high, not much inferior to that of iron, on the
scale of Wedgwood as 130 to 158 ; i,t suffers
little change from beirig exposed to air or
water at common temperatures. Like iron, it is
attracted by the magnet, and is capable of being

[ 413 3

rendered permanently magnetic. When fused
on charcoal, and acted on by a stream of
oxygene gas it burns briUiantly, throwing off
bright sparks.

S. Cobalt combines with oxygene ; when kept
red hot for some time it becomes covered with
a dark powder, and by being long exposed to
air in a state of intense ignition, it is entirely
oxidated, and in this process, according to
Klaproth, 100 grains of the metal became 118
grains of oxide. This oxide though it appears
blackj is in fact deep blue, and gives this tint
to glass. It seems to be cobalt in its first state of
oxygenation, and when dissolved by acids and
thrown down by fixed alkalies, forms the basis
of « kydrat of a bright blue colour. By heating
the hy drat gently in the air^ it gradually becomes
black, loses its water, and absorbs oxygene.
This black powder has the property of decom-
posing muriatic acid ; its excess of oxygene
combines with the hydrogene, and the chlorine,
is set free. From a rude experiment I am in-
clined to conclude that the oxygene in the black
powder from cobalt is to that in the blue oxide
as 2 to 3. If Klaproth's experiments be
made the ground work of calculation, and the

r

blue oxide be considered as a deutoxide, theu
the number representiog cobalt will be J 66, and
the blue oxide will consist of 166 of cobalt
and 30 of oxygene ; and the black oxide of

C 414 ]

166 and 45. Mr. Thenard states that there is
an olive oxide of cobalt, produced by exposing
the blue powder, which must be regarded
as a hydrat, to air at common temperatures.
And Mr. Proust has stated that there is a red
Iiydrated oxide of cobalt ; it is probable that
this last is a compound of the black oxide and
water; and the substance supposed by Mh
Thenard to be an olive oxide, a mixture of the
two hydrates.

4. Cobalt combines with chlorine : the com-
pound may be obtained by introducing chlorine
into an exhausted retort containing; the metal
in fine powder and gently heating it ; a combus-
tion takes place, but the results of this combus-
tion have not yet been accurately exarriinedi

5. Cobalt is not known to enter into com-
bination with hydrogene, azote, carbon, or
boron.

6. Cobalt combines with sulphur and phos-
phorus, but with considerable difficulty. The
sulphuret is formed by acting on oxide of
cobalt in a state of ignition by sulphur, and
according to Proust, it consists of 71. 5 parts
cobalt and 28.5 of sulphur ; which indicate
uearly one proportion of metal 166, and two of
sulphur, 6o. The phospkuret is made "by drop-
ping phosphorus upon ignited cobalt ; it has
not been minutely examined, nor its composi-
tion ascertained.

[ 415 i

7. The action of the metals of the alkalies
and earths on cobalt has not been examined.

8. There are no accurate experiments onth^
€ombinalions of pure cobalt with the common
metals. Lead unites with it, as Gmelin has
shewn, and forms an alloy less malleable in
proportion as it contains more cobalt.

9. Cobalt in its metallic state is not employed
in the useful arts. In its state of combination,
with oxygene, it is used to give glass, porce-
lain, k.c. a rich blue colour. One grain of the
pure oxide will give a deep tint of blue to 240
grains of glass. The solution of the oxide of
cobalt in muriatic acid, forms one of the most
beautiful of the sympathetic inks. This solution
when concentrated is pale rose-coloured in
the cold, but beomes blue green when heated;
letters or figures traced by it upon paper are
invisible in the cold, but become blue ereen
when held before the fire.

£2. Copper, Cuprum.

1 The copper of commerce is procured from
the native combinations of this metal with sul-
phur, oxygene, and certain acids, by roasting
and fusion either alane or with lime and car-
bonaceous substances ; it is not however quite
pure. To obtain it in a state of purity— dis«
solve copper in strong muriatic acid, dilute the

1416]

solution witii water, and put into it a polished
plate of iron, the copper will be precipitated'
in its metallic state : it should be washed
in dilute muriatic acid and then with pure
water,

2. Copper is of a red colour, it is a little harder
than silver, its specific gravity is about 8.89.
When rubbed it emits an unpleasant smell, and
it has a disagreeable taste. It is very malieablet
has considerable ductility, and in tenacity is su-
perior to all the metals except iron; it fuses at a
low white heat. By exposure to the air copper
becomes tarnished, and after some tijne is coated
with a green crust, which consists of the metal
in union with oxygene and carbonic acid.
Copper is not affected by being kept in water,
nor does it decompose this fluid at any tempe-
rature.—It burns with a red flame edged with
green, when fused and acted upon by oxygene,
when in thin leaves it inflames spontaneously
in chlorine.

3. Two compounds are known, consisting of
oxygene and copper. One is found native, and
is the rub/ copper ore. It occurs in octaedrons
of a considerable lustre, its powder is dull
orange red. According to Mr. Chenevix it
contains 11.5 per cent, of oxygene ; according
to Mr. J. Davy about 11 per cent. It is soluble
in solution of muriatic acid ; and when this

[ 417 ]

solution is precipitated, a pale orange coloured
powder falls down, which is this oxide united
to water. The other oxide of copper is formed
in the combustion of copper, or by heating the
precipitate from a nitrous solution of copper by
potassa to redness. It is a black powder, and
appears, from various experiments, to contain
about 20 per cent, of oxygene; when it is
precipitated from acids by potassa it is in
combination with water, and is then pale blue;
a!id, as 1 have found, contains 10 per cent,
of water. If the red oxide of copper be
considered as a protoxide and the black a
deuloxide, the number representing copper
will be 120, and this number will be found to
correspond accurately with that gained from
the analysis of the other combinations of the

.metal. The number representing the protoxide
is 135 and tiiat representing the deutoxide 150,
and that representing the blue hydrat I67.

4. As there are two combinations of copper
and oxygene, so there are likewise two com-
binations of this metal with chlorine ; both aie

.produced at the same time, by the combustion
of the metal in chlorine ; one is a fixed easily
fusible substance, like rosin in its exterior cha-

; racters, the other is a yellowish sublimate. The
fii:st of these, as appears froni the analysis of

■ Mr. John Davy, consists of 36 chlorine, and

5 VOL. I. E; C: ■

t 4iS ]

64 copper ; and the second of 53 cblorhie and
47 copper ; the first may be called cupraney the
second cupranea. Guprane may be formed
likewise by heating strongly together a ir^ixture
of one part of copper filings, and two parts of
corrosive sublimate ; and it was in this way first
produced by Boyle, who appears to have been
its discoverer. Guprane is converted into cu-
pranea by being heated in chlorine. Guprane
may be regarded as consisting of one propor-
tion of copper 120, and one of chlorine 67 ;
and cupranea of one of copper 120, and two of
chlorine 134, Cupiane is not soluble in water,
but slowly becomes green by the action of the
atmosphere; when introduced into the flame
of a candle, it produces a most beautiful lio-ht
possessing almost all the prismatic colours.
Cupranea dissolves in water and givesit a o-reen-
ish colour ; it is decomposed by a strong heat,
and converted into cnpranej^y the expulsion
of oxygene.

5. Gopper readily combines with sulphur,
producing ignition when they are fused to-
gether; and they form together a substance
more fusible than copper, brittle, and of a
deep gray colour. This substance is likewise
found native, and according to the analysis
cf Mr. Ghenevix, contains about 19 per cent»
of sulphur. The artificial sulphuret in some
synthetical experiments which I made upon

[ 419 ]

it, appeared to contain from 21 to 19 per
cent. It may therefore be regarded as com-
posed of one proportion of copper 120, and
one of sulphur 30. It is probable that a saper-
sulphuret of copper may exist: some of the
golden coloured copper pyrites, which contain
as much as 41 per cent, of copper, afford from
35 to 45 of sulphur: but they likewise contain
iron. No supersulphuret has as yet been made
artificially.

6. Copper combines with phosphorus, by
fusion. The phosphiiret is of a white colour and
very brittle-, its specific gravity is 7.1220. It
Avas first formed by Margraaf, According to
Pelktier it contains 20 per cent, of phosphorus;
and allowing this estiaation it must be com-
posed of two proportions of metalj and three
of phosphorus, 240 and 60.

7. Copper has not yet been combined with
hydogene, azote, carbon, or boron.

S. It unites to the fixed alkaline metals, and
to all the common metals that have been de^-
scribed. Some of its alloys with the common
metals are well known. Copper is rendered
yellowish white by alloy with a small quantity
of manganesum. United to zinc, copper pro-
duces brass, Dutch gold, Rupert's metal, and
pinchbeck : from a third to a twelfth of zinc
is used ; the paler the alloy required, the
larger the quantity of zjae.

[ 420 ]

Copper with a fourth of its weight of lead,
forms pot metal. Copper alloyed with from
YT -f of tin forms the different species of
bronze and bell-metal. The best composition
for the mirrors of reflecting telescopes is a com-
bination of 32 parts copper, 15 parts tin, 1 part
brass, 1 silver, and 1 of arsenic. TiUcnag, ac-
cording to Keir, is a white alloy of copper, zinc
and iron.

9. The account of the alloys of copper proves
its importance in the arts. It is used unalloyed
likewise for various important purposes, such as
sheathing ol" ships, forming vessels when united
with other metals, for culinary purposes, See
In early ages the alloys of copper formed the
principal arms olFensive and defensive. 1 have
examined an ancient Attican helmet which
consisted of an alloy of copper and tin. The
swords and spear-heads of the early inhabitants
of Greece and Italy seem to have been composed
of the same materials.

All the saline combinations of copper are
poisonous.

23. Mckel or Mickolim.
JSlckel was discovered by Groastedt in J 751,
and examined in its pure state by Beigman, in
1773. Nickel exists in an ore called kupfer-
nickel combined chiefly with sulphur, or in
nickel ochre, in which it is imited to osy^ene.
The metal may be obtained from these ores by

[ m ]

roastmg and ignition with charcoal ; but in this
case it is far from being pure. Piwe nickel, or,
at least nickel free from any other metallic sub-
stance, may he procured by nearly the same
process as cobalt. The precipitate from the
aramoniacal solution by solution of potassa,
contains the nickel, and this precipitate must
he intensely heated with charcoal powder.

2. Nickel is of a white colour, and possesses
considerable lustre ; its hardness is little in-
ferior to that of iron: its specific gravity is
about 8. 3S, but when forged it increases to
8.82. It is ductile and malleable. It requires
a stronger heat for its fusion than iron — like that
metal it is attracted by the magnet. When in
fusion it burns like iron under a stream of
oxygene gns.

S. Nickel when intensely ignited, exposed
to air, becomes a dark brown powder, which
is still attractable by the magnet. Its solution
in nitric acid decomposed by pptassa affords a
pale grass green hydrated oxide, which contains
more than a fourth of its weight of water, and
which when heated to dull redness becomes an
oxide of a pale ash gray colour, and which,
according to Tupputi, is composed of 21.2 parts
of oxygene, and 78.8 of metal ; this oxide by
strong ignition becomes darker coloured, but
wheri pure cannot be reduced to the metallic
state by heat alone. Another oxide of nickel

[mi

lias been described by M, Tlienard containing
more oxygene. It may be procured by acting
on the hydrat of nickel by the salts called hy-
peroxymnriates ; it is of a black colour ; its
composition has not been accurately ascertained.
From the nature of the compounds of nickel
and sulphur, to be discussed immediately, it
seems probable that the gray oxide is a deut-
oxide ; and if this be allowed, the number re-
presenting nickel will be 111, and the gray
oxide will be represented by two proportions of
oxyg,ene SO added to one proportion of metal.

4. Nickel when strongly healed in chlorine,
smokes and produces an olive coloured sub-
stance ; but the composition of this substance
has not been ascertained, nor its properties ex-
amined. When muriate of nickel is decora-
posed by heat some white brilliant scales are
formed, which, as appears from experiments
made by Mr. E. Davy, consist of nickel and
chlorine; but their composition has not been
exactly ascertained.

Sulphur combines with nickel by fusion,
and forms a bright gray sulphuret, possessing
metallic lustre. From experiments made on this
mlphuret by Mr. E. Davy, it appears to contain
about 34 per cent, of sulphur, which gives pro-^
portions corresponding nearly to one propor-
tion of metal 111 and two of sulphur 60, and
harmonizes with the supposition that the olire

[ 423 ]

oxide is a deutoxide. Tlie same enquirer states
that there is a supersulpliuretj which may be
formed by heating the gray oxide with sulphur,,
and which contains about 56.5 of nickel to 43-5i
of sulphur, and which agrees nearly with one
proportion of metal to three of sulphur.

6. Fhosphuret of nickel may be formed by
causing phosphorus in vapour to act on me-
tallic nickel in ignition ; the phosphuret is
almost black and has metallic lustre. Its compo-
sition has not as yet been accurately determined,

7. Some specimens of nickel alFord carbon
during their solution in acids ; but no definite
compound of carbon and the metal has been
obtained. Nickel has not yet been combined
with hydrogene, azote, or boron, nor have
any accurate experiments been made on its
action on the metals of the fixed alkalies.

8. It forms alloys with some of the common
metals ; but few of these compounds have been
examined with attention : with tin it produces
awhite brittle compound. Its alloy with copper
is less ductile than pure copper, and is slightly
inaffnetic. Its combination with iron is the
most interesting of these compounds ; these
metals seem to unite in ail proportions ; the
colour of the alloy approaches nearer to that
of silver in proportion as the nickel prevails,
and the iron retains its malleability. In all the
meteoric stones that have been examined it is

[ m ]

remarkable that tlie iron is alloyed by froiir
1.5 to 17 per cent, of nickel. The masses
of iron found in Siberia and Soutli America
contain nickel, and there is the strongest pro*-
habiiity that they are likewise of meteoric
origin. The alloy of iron and nickel is much
Jess liable to rust than common iron, and it
is likely may be advantageously applied in the
useful arts. The oxide of nickel is employed
to give colours to enamels and porcelain; iii
different mixtures it produces brown red, and
grass wreen tints,

24. Uranium

1. Uranium was discovered by Klaproth In
1 789. It may be procured from the ores Cxilled
Pechblende, and Uranochre, by the following
process. Let the ores be boiled in moderately
diluted nitric acid, and solution of sulphate of
soda added, and the precipitate, if any, separated.
The clear solution is to be acted on by solution
of potassa, the precipitate digested in ammonia,
and the residuum heated with strong nitric acid,
and evaporated to dryness. The clear solution
obtained from the mass by pure water whep
precipitated by solution of potassa will afford
a yellow powder, and this made into a ball
with wax, and intensely ignited in a crucible of
charcoal, affords metallic uranium.

^, Uranium i$ of an iron gray colour and h^s

[ 425 ]

considerable lustre ; it is hard and brittle. Its
specific gravity, according to Klaproth, is 8.1,
its fusing point is higher than that of manga-
nesum. It undergoes no change by exposure to
air, but when heated strongly, burns, combines
with oxygene, and assumes a blackish colour.

3. Two compounds of uranium and oxygene
have been examined by Klaproth ; the preci-
pitate thrown down from the solution of ura-
nium in nitric acid when heated to dull redness
is still yellow, and this treated with oil and in-
cinerated slightly, so as to burn off the oil,
becomes a black oxide. It appears probable
from Bucholz's experiments, that the oxygene
in the black oxide is to that in the yellow as
1 to 3, and that the yellow oxide contains about
80 of metal and 20 of oxgene. I found that 8
parts of potassa precipitated 8.2 parts of yellow
oxide of uranium from the saturated nitrous
solution; and from this experiment, if potassa
and the yellow oxide of uranium be supposed
analogous in composition, 76.8 will be the num-
ber for the metal, and the black oxide must be
a compound of three proportions of metal with
one of oxygene. The substance that has been
called the native oxide, and which is crystallizeiJ
in quadrangular plates, is, I find, a hydraied
oxide. Bucholz supposes that there are several
different oxides of uranium ; but he founds his
opinion upon the different colours of precipi-

[ 426 ]

tates, wliich may be mixtures of hydrates of the
two oxides.

4. No experiments have as yet been mada
Oil the action of uranium on chlorine, hydro-
gene, azote, boron, the metals of the fixed alka-
lies, or the common metals.

5. A sulphuret of uranium may be procured
by igniting the oxide with sulphur. It is a
"black heavy powder : its composition has not
been ascertained.

6. Uranium has been hitherto found in quan-
tities too small to render it applicable to the
purposes of the arts. Its oxides give bright
colours to glass, which according to the propor-
tions are brown, apple green, or emerald green.

2§. Osmium.

1. This metallic substance was discovered by-
Mr. Tennantin I8O4. it may be obtained from
crude platina, by dissolving all the soluble
parts in aqua regia, and distilling the black
powder that remains with nitre, at a heat under
redness ; a sublimate rises, which is soluble in
water. When mercury is shaken with the so-
lution, an amalgam is formed, and by distilling
off the mercury, pure osmium is obtained.

2. This metal has been procured only in very
minute quantities ; it is of a dark blue colour, has
not been fused, nor does it undergo any change
at the most intense hsat unless in contact with
air, when it is converted into a volatile o^ide.

S. The composition of the oxide of osmmm
has not been ascertained ; it is a solid semi-
transparent substance, having a sweet taste and
a strong smell : it is soluble in water, combines
with potassa, and makes witli it an orange solu-
tion in water. It tinges the skin of a dark colour;
and produces a purple with solution of galls.

4. No corabirtationsof osmium with any of ths
undecompounded substances described in the
foregoing sections except that with oxygene
have been examined. The metal is not soluble
in any of the acids ; but when fused with the hy-
drat of potassa becomes oxidated and combines
with the potassa. It is a metal very easily re-
duced, being precipitated from the aqueous
solution of the oxide by ether or alcohol,

26. 'Tungsten or Tungstenuni.
1. Tungstenum is obtained from a mineral
known by the name wolfram; it contains the
oxides of tungsten, iron, and manganese, with
earthy matter. To procure the metal pure, boil
finely pulverised wolfram in strong muriatic acid
for some time; separate the solution ; the resi-
duum contains a yellow powder; it is to be
washed, dissolved in ammonia, evaporated to
dryness, then mixed with a little fine charcoal
powder, and exposed to a very intense heat fot
about ^0 minutes in a covered hcssian crucible.
Small grains of pure tungstenura will be found
^t thebotlom of the crucible.

[ 428 ]

Tungstenum in its metallic form was first
procured by Messrs. D'EIhuyars, in 1782.

5. Tungstenum is of a grayish white colour,
and has considerable lustre. Il is hard and
rather brittle. Its specific gravity is about I 7.3.
It requires the strongest heat of a forge for its
fusion. It is scarcely affected by exposure to air
at common temperatures. At 'a temperature
below redness its surface exhibits iridescent
colours like iron»

3. Tungstenum combines with oxygene.
When the metal in fine powder is heated to
rednessj it soon acquires a yellow colour, and is
gradually converted into a yellow oxide, which is
not soluble in water. Its specific gravity is 61?,
water being 100. It is very difficultly fusible.
According to Messrs. D'EIhuyars lOO grains of
metal by calcination form 124 grains of yellow-
oxide. Supposing the oxide a deutoxide, this
result would give the number representinq;
tungstenum as 125, and the number represent-
ing the yellow oxide as 155. Taking Klaproth's
analysis of the combination of tungstic acid and
lime,* as the basis of calculation, and supposing
double proportions of the oxide to one propor-
tion of lime, the number representing the yellow
oxide will be 124. From this it is probabje
that in D'EIhuyars' experiments the metal was
not entirely converted into oxide; and that
• 17 of lime, 77 of tungstic oxide.

[ 429 ]

the number is about 94 ; but new experi-
ments are wanting to elucidate this point.
When the yellow oxide of tungstenum is di-
gested with solution of tin in muriatic acid, it
becomes blue from loosing oxygene. It is pro-
bable that in this state it is a protoxide, but nO
accurate researches have been made on this blue
substance.

4. Tungstenum, I have found, burns with a
deep red light when heated in chlorine, and
forms an orange coloured volatile substance,
which affords the vellow oxide of tunp-stenura,
and muriatic acid, when decomposed by water. I
have made no experiments, nor are any, I believe,
on record on the composition oi' liingsteuaiie.

5. Sulphur and phosphorus are both capable
of being combined with tungstenum by being
made to act upon it in a state of ignition ; but
the properties of the sidphuret and phosphuret
have not been examined accurately.

6. Tills substance has not been combined
with hydrogene, azote, carbon, boron, or the
metals of the fixed alkalies. From the experi'
menls of Messrs. D'Elhuyars, it appears to
unite with most of the common metals; but its
alloys have been only rudely examined.

7. Tungstenum and its oxides have as yet
been applied to no uses : it was stated by Guylon

^ de Morveau that the yellow oxide formed a
mordant useful in dyeing ; that the red juices

t 430 ]

of fmils \vQVQ fixed by it, so as to make per-*
manent and beautiful lakes, The dyers who have
tried the experiments in this country have not,
however, given a favourable report of the results,

27. Tilanium.

1. Titanium is obtained from a mineral lonir
known by the name of red schorl, or titanite.
The mineral in powder is to be fused with five
or six times its weight of subcarbonate of po-
tassa ; the mass is to be fully exposed to the
action of water, and the solid matter remaininfr
digested and boiled with muriatic acid. The
white powder not dissolved, when mixed with
oil, and intensely heated in a crucible of char-
coal, affords titanium. The oxide of titanium
was discovered by Mr. Gregor, in 1781, in an.
ore found in the valley of Menachan in Corn-
wal ; but metallic titanium was not produced
till 1796, by Vauquelin and Hecht.

2. Little is known concerning the physical
^and chemical properties of litanhm; it has
only been procured in minute quantities, and
in an imperfectly reduced state. Its colour
resembles that of copper. It has much lustre.
It is brittle. It tarnishes by exposure to air;
and requires the most intense keat of a forge
even for its imperfect fusion.

3. Titanium combines with oxygene when it
is exposed to heat in the atmosphere, and ac-
quires a blue colour. The red oxide, whicli

Corttams a larger proportion of oxygene, is
found in the mineral kingdom. There is a pow-
der of a white colour procured by fusing the
fed oxide with potash. This has been supposed
to be a peruxide, but is probably an hydrate^
oxide; no precise experiments have been made
on the composition of these bodies. This white
powder is insoiuble in acid and alkaline solu-
tions: and becomes yellow by being heated.

4' The combination of titanium with chlorine
has not yet been made.

5. Titanium is not known to combjiie witl^
hydiogene, azote, carbon, or boron.

6. Titanium has not yet been combined witih
-sulphur. It enters into union with phosphorus.
The phosphuret is brittle, and has metallic
lustre. Its composition has not been determined.

7. The agency of the metals of the alkalies
on titanium has not been examined. It has
not been combined with any of the common
metals ej^cept iron ; and this aiioy is not cha-
racterised by any remarkable properties.

8. Titanium has not been employed in the
arts except for one purpose; its oxide has been
used at Sevres in the manufacture of porcelain^
to impart a brown colour.

28. Coliimbium.
1. Columbium exists in an ore brono-hJ*
from North America, of a black colour; and
likewise In two substances found in Sweden

t 43^ ]

called tantalite and ittrotantalite. The metal
may be procured by igniting the ores with
hydrated fixed alkali; and saturating the alkali
with nitric acid, a white powder falls down.
This powder was first obtained by Mr. Hatchett
from the American specimen, in 1S()2: and
soon after the same substance was procured by
Ekeberg from the Swedish mineral, and Con-
sidered by him as a new substance. Dr. Wol-
laston, in 1810, demonstrated the identity of
the two bodies,

2. The white powder combines with alkalies
and metallic oxides, and reddens litmus paper.
Hence Mr. Hatchett named it columbic acid»
Attempts were made to reduce it by ignition
with charcoal, in the same manner as the oxide
of titanium, but without success; it became black,
but did not acquire the metallic lustre. By
passing potassium in vapour ilirough the white
powder, heated to redness, I found that the
potassium became converled into potassa, and
a dark coloured brilliant powder, like plumbago,
■yvas produced. This is probably the metallic
basis yf the substance, or pure columbium,

3. . No experiments have been made upon
the combinations of this substance. The white
powder is soluble in boiling sulphuric acid ;
and it is precipitated from its solution of an
olive colour by triple prussiale of potash, and
of a bright orange by solution of galls.

[ 433 ]

29. Cerium,

1. There is a mineral found at RIdderhytta
in Sweden, very like tungsten, of a reddish
colour, and which has been called cerite. From
this substance, Hissinger and Berzelius, in.
1804, extracted a brown powder, having the
characters of a metallic oxide, and which they
named oo'ide of cerium. To procure this pow-
der, the ore is digested with solution of nitro-
muriatic acid ; and the solution obtained eva-
porated to dryness, and heated with a little
muriatic acid ; the solution so procured is to be
precipitated by solution of ammonia, the preci-
pitate redissolved in muriatic acid, and acted
upon by solution of hydrosulphuret of potassa;
the clear liquor, precipitated by solution of
carbonate of potassa in excess, affords a white
powder, which, when heated to redness, affords
the br own oxide of cerium.

2, Cetium had not been obtained in the me-
tallic form till I succeeded in reducing some
oxide sent me, by M. Berzelius, by means of
potassium^ poiasda was formed, and a deep
gray metallic powder, which became brov/n by
oxidation.

S. When the brown oxide of cerium is di-
gested in the mineral acids, it becomes dissol-
ved;, and is thrown down from those solutions

VOL. I F f

C 434 3

by alkalies^, as a white powder: it is supposed
that this powder contains less oxygene than
the brown oxide ; but it is probably a hjdrat.
As yet, no experiments have been made either
on the composition of the brown oxide, or the
white powder.

4. No researches have as yet been made on
the combinations of cerium with the other un-
decompounded bodies. The solutions of cerium
are not precipitated by solutions of galls ; they
give a white precipitate with the triple prussiate
ofpotassa.

30. Palladium.

1. Palladium was discovered by^Dr, Wollas-
ton, in 1803. It exists in the ores of platinum,
both those from Peru and the Brazils. It may
be procured by dissolving crude platina in aqua
regia, and precipitating the saturated solution
by solution of prussiate of mercury. The pre-
cipitate, washed, dried, and exposed to a strong
heat, is converted into palladium.

2. The colour of palladium is white, resem*
bling that of platinum. Its hardness is rather
greater than that of bar iron. Its specific gravity
varies from 11.3 to 11.8. It is very malleable, but
has little ductility. It fuses at a high tempera-
ture; but the precise point has not been deter-
mined. It is not alfectcd by air or water at

i 435 ]

common temperatures. When it is heated
strongly, its surface acquires a blue colour.

3. Palladium combines with oxygene and
chlorine by heat ; but neither its oxides nor
its combinations with chlorine have as yet been
examined. Dissolved in nitric acid it forms a
beautiful red solution, from which the alkalies
throw down an orange coloured powder, which
probably is a hjdrated oxide.

4. Palladium readily combines with sulphut
when they are heated together in a glass tube.
The sulphuret is rather paler than the metal,
and very brittle: in an experiment that I made,
6.1 grains of palladium gained 1.5 grains, by
being converted into the sulphuret; and suppos-
ing the sulphuret to consist of one proportion
of metal, and one of sulphur, the number repre-
senting palladium will be 1 34.

5. Palladium seems to have no action oft
hydrogene, azote, or carbon. Its relations of
attraction to boron, and the metals of the fixed
alkalies, have not yet been examined. It forms
alloys with most of the common metals; but
the properties of these compounds have not
been examined with attention.

Palladium has not as yet been found in sulK-
cient quantities to be applied to the purposes
ol' the arts.

[ 436 ]

31. Iridium.

1. Iridium was discovered, in 1803, by Mr.
Tennant ; before Mr. Tennant had published
his experiments, it was likewise discovered by
M. Descotils.

Iridium exists in minute quantity in the crude
ore of platina. To obtain it, the black powder
(remaining after the solution of the ore of platina
in nitro muriatic acid) is to be mixed with about
five times its weight of pure soda, and heated
to redness in a silver crucible for about 30
minutes. The dry mass is to be dissolved in
diluted muriatic acid, and the undissolved re-
siduum is to be alternately treated with alkali
and acid ; by which means it will be all taken
up. The solution, containing an excess of mu-
riatic acid, is to be evaporated to dryness, re-
dissolved in pure water, and slowly evaporated,
so long as any octohedral crystals form. These
crystals are muriate of iridium, and are reduced
to the metallic state by exposing them for a short
time to an elevated temperature in a platinum
crucible.

2. Little is known concerning the properties
of this metal. Iridium is of a white colour. It
is brittle ; and required for its fusion a most in-
tense heat: it im probable that its specific gravity
is higher than that of platinum. It is not acted

[ 437 ]

upon by oxygene even when heated to white-
ness. From its relations to muriatic acid, which
dissolves it, it seems that it is capable of unit-
ing to chlorine.

3. Iridium has not been combined with hy-
drogene, azote, sulphur, phosphorus, carbon, or
boron, or the metals of the alkalies. It unites
to lead ; and forms a malleable alloy with
copper. Dr. WoUaston has found amongst the
grains of crude platina small white particles of
specific gravity 19.25; which consist of indium
alloyed with osmium, and no other metallic
substance. The osmium may be oxidated by
the water in hydrat of potassa, and united with
the potassa ; and the iridium combined with
chlorine by treatment with muriatic acid, and
thus dissolved.

S2. Rhodium.

1. Rhodium was obtained by Dr. Wollastoa,
in 1804, from the ore of piatina, by the follow-
ing process. The ore is dissolved in dilute
aquaregia; a solution of sal ammoniac is added ;
the clear liquor, separated from the precipitate,
is acted on by a rod of zinc. By the zinc, a
black powder is thrown down, which is washed
with very diluted nitric acid. This black pow-
der is redissolved in dilute aqua regia; to this

[ 438 ]

solution some common salt is added; the wbole
is then evaporated to dryness, and wi*shed by
alcohol, till it has dissolved all the soluble mat-
ter; there remains behind a deep red substance,
which, when dissolved in water, and acted on
by a rod of zinc, affords a metallic powder,
which, intensely ignited with borax, gives a
metallic button of rhodium,

2. The specific gravity of rhodium exceeds
1 L Its colour approaches to that of silver, with
a tint of yellow. It is not acted upon by nitric
or sulphuric acids. It is not known whether
it combines with oxygene; but solution of
potassa throws down a yellow coloured powder
from the red crystals obtained by dissolving in
water, the powder left after the washing by
alcohol, and evaporating, so as to permit crys^
tallization. From the action of nitro-muriatic
acid on rhodium, it is probable that it combines
with chlorine.

3. Rhodium unites with sulphur, and is ren-
dered easily fusible by it. It likewise combines
with lead, copper, and bismuth ; and its alloys
are easily soluble in nitro-muriatic acid.

33. Mercury, or Merciirium.

1. Mercury has been known from the earliest
ageji of the world. It is found native in the

[ 439 ]

mines ofldria, Spain, and Peru; and likewise
combined with sulphur in cinnabar, from which
it is separated by distillation with quicklime

2. Mercury is of the specific gravity 1-^.56.
Its colour is a brilliant white- It is fluid at the
common temperature of the air; and becomes a
solid at 39° below 0 of Fahrenheit's scale: at
about 660° it boils. It is capable of being burnt
when the Voltaic flame is made to act upon
it, and it produces a brilliant greenish lig,ht:
its capacity for heat has been referred to
page 77.

3. There are two well known compounds of
mercury and oxygene, one black and the other
red ; the first may be made by keeping mercury
long in agitation, as, for instance, by fastening
it in a bottle containing much air, to a mill
wheel. The second is produced by keeping
it heated in the atmosphere for a long while,
nearly at its boiling point. The black oxide
of mercury may be likewise made by acting on
calomel by solution of potassa ; and the red
oxide by acting on corrosive sublimate by the
same substance, and gently heating the pre-
cipitates after they are washed. The black
oxide changes when gendy heated in the air,
and becomes the red oxide. Both the black
and the red oxides of mercury are decomposed
by a strong heat ; the mercury revived and
oxygene liberated ; from experiments on their

[ 440 ]

decomposition I ascertained that the quantity
of mercury being the same, the red oxide eon-
tamed exactly twice as much oxygene as the
hJack ; and my results give the number repre-
senting mercury about 380, the protoxide or
black oxide as composed of 380 mercury and
15 oxygene, and the red oxide or deutoxide as
constituted by 38O metal and 30 oxygene. It
has not yet been ascertained whether these
oxides can be combined with water, so as to
form hydrates.

4. Mercury combines with chlorine : when
the metal is heated in the gas ; it burns with a
pale red flame, and the substance called corro-
sive sublimate is formed. When corrosive sub-
limate is long rubbed with mercury till they
afe incorporated together, and the mass sub-
limed, the substance called calomel is formed.
I have found by a minute analysis, that the
quantity of chlorine in calomel is to that in
corrosive sublimate as 1 to 2, the quantity of
mercurvbeiniT the same in both. Calomel is taste-
less, corrosive sublimate has an acrid burning
taste; calomel is insoluble, corrosive sublimate
soluble in water. Calomel, according to my ana-
lysis, consists of one proportion of mercury 3SO,
and one proportion of chlorine 67. Corrosive
sublimate of 3S0 metal, and 134 chlorine. The
names tnercurane and mercurana^ which may
be adopted to signify the relations of their com-

[ 441 ]

position, are too similar to each other to be
safely used as familiar appellations for the two
substances, as corrosive sublimate is a powerful
poison, calomel an excellent medicine.

5. Sulphur and mercury readily combine
by fusion ; three parts of mercury and one of
sulphur melted together, heated to redness,
and then sublimed out of the contact of air,
afford a cake of a fine red colour, called cin-
nabar^ and known in commerce under the name
of vermilion. It seems from the experiments
made on this substance, that it contains one pro-
portion of mercury, and two of sulphur. When
sulphur and mercury are heated strongly toge-
ther, but not to sublimation, a black mass is ob-
tained, which has been called Ethiops mineral.
It is probable that this substance contains a
larger quantity of sulphur than cinnabar, but its
composition has never been ascertained, and it is
always converted into cinnabar by sublimation.
The specific gravity of cinnabar is about 10,
that of Ethiops is less: both these substances
are easily decomposed by any metal having a
stronger affinity for sulphur ; when heated with
iron filings, for instance, the sulphur combines
with the iron, the mercury rises in vapour and
condenses. ,

6. I have made a combination of phospho-
rus and mercury, by strongly heating together

C 442 ]

p^sosphorus and calomel. It is of a chocolate
colour, and not fusible at the boiling; point of
mercury, I have made no experiments on its
composition.

7. No combinafions have as yet been effected
of mercury with hydrogene, azote, charcoal, or
boron.

8. Mercury unites readily with potassium
and sodium, and forms solid alloys ; the com-
bination is attended with much heat. 1 part of
potassium renders solid at common tempera-
tures 70 parts of mercury. These amalgams ^
for so the metallic combinations of mercury are
called, are of the colour of silver; the mercury
rises from them at a heat below redness. The
alkaline metals are rapidly separated from the
mercury by the oxygene of air or water.

9. Mercury combines with most of the common
metals described in the preceding pages, and
forms amalgams with them. It unites most
readily with the easily fusible metals, but few
researches have been made on its union with
the diflBcuhly fusible metals, as its volatility
renders it difficult to make the experiments
under favouiable circumstances.

10. Mercury is a very important and useful'
metal. It is employed for extracting gold and
silver from their ores. It is used in amalgamation
Vi'iih tin for covering mirrors. The sulphuret

[ 443 ]

forms the most perfect red pigment as yet
discovered. Its oxides and combinations with
chlorine constitute some of the most important
substances employed in pharmacy.

34. Silver^ or Argentum.
I. Silver is found native, or is procured from
ores, which are principally combinations of
silver with other metals or with sulphur, but
the silver of commerce is not pure. To obtain,
it pure; the metal must be dissolved in -nitric
acid, and the solution mixed with solutioQ
of common salt until no further precipitate
takes place. The precipitate must be washed
and ignited strongly with about three times its
weight of subcarbonate of potassa, mixed with
a little charcoal in powder, for half an hour ; a
button of pure silver will be procured.
. 2. Silver is of a brilliant white colour. It
has no taste or smell; it has great lustre. Ita
hardness is inferior to that of copper :
specific gravity is about IO.40, and it is slightly
increased by being hammered. It yields to none
of the metals except gold in malleabiliiy. It is
very ductile, and may be readily diitwa out
itito extremely fine wire. Its tenacity is con-
siderable. A wire of 0.0 7 B of an inch iu
diameter will support 187.13 lbs. weighu Its
fusing point is about 1000° Fahienheit. It

[ 444 ]

tarnishes slowly in the air ; and this tarnish
is owing to the presence of fumes containing
sulphur.

3. Silver enters into combination with oxy-
gene ; it absorbs this gaseous principle when
kept intensely ignited in an open vessel for
some time, and is converted into an olive-
coloured glass. It burns with a fine green
flame, and is converted into an oxide when
acted upon by a powerful Voltaic instrument.
» The olive oxide of silver is likewise obtained
by dissolving the metal in nitrous acid, pre-
cipitating by aqueous solution of baryta, and
heating the precipitate to dull redness. From
my experiments 1 conclude that 100 of silver
absorb about 7-3 parts of oxygene to become
the brown oxide ; and supposing this oxide to
be composed of one proportion of metal aud
one of oxygene, the number representing silver
will be 205. No other oxide of silver except
the brown is certainly known.

4. Silver combines with chlorine when the
metal is heated in contact with the gas. The
compound, which may be called argentane, has
been long known by the name of hornsilver.
It is a whitish serai-transparent substance, cuts
like horn, is fusible at a red heat, and is inso-
luble in water. It contains about 24-5 percent,
of chlorine, and may be considered as consist-

[ 445 ]

ing of one proportion of silver 205, and one of
chlorine 67 .

5- Silver is not known to combine with hy-
drogene, azote, carbon, or boron.

6. Silver and sulphur combine. This com-
bination is effected, according to M. Proust,
when silver is exposed for a considerable time
to the atmosphere; it is readily formed by
heating to redness thin plates of silver and sul-
phur. It is of a black colour, is brittle, and
has the metallic lustre. According to the
experiments of Wenzel, 100 parts ol silver by
fusion combines with I4.7 parts of sulphur.
The sulphuret of silver may therefore be re-
garded as constituted by one proportion of
silver 205, and one of sulphur 30.

7. Silver combines with phosphorus. This
compound may be made according to M. Pelle-
tier, by heating to redness a mixture of silver,
phosphoric glass, and charcoal powder. It is a
white brittle substance ; its composition has not
been determined with precision.

8. Silver has not yet been combined with
hydrogene, azote, carbon, or boron.

9. The action ot the metals of the alkalies
and earths on silver has not been examined.
Sliver forms alloys with most of the other
metals, but the greater number of them have
not been examined with much attention,

[ 446 ]

or been applied to the purposes of the arts.
The alloy of silver and copper is employed in
coins. It is harder than pure silver, and better
adapted to receive a fine impression

10» Silver is employed for a great variety of
purposes in the useful and ornamental arts.
It is largely used for silvering copper, brass,
and sometimes iron. In the common form in
which it is applied, it is alloyed with -J^-of cop-
per, which gives to it hardness, without im-
pairing its colour or its lustre.

35. Gold, or Aurum.

1. Gold is found native, alloyed with copper
or silver. To obtain it in a state of purity. Gold
is dissolved in nitro muriatic acid, the silver will
remain an insoluble muriate, and must be sepa-
rated ; to the clear solution a solution of green,
sulphate of iron must be added; the gold will be
precipitated in the state of a fine powder, and
after being well washed in diluted muriatic acid,
and then in distilled water, may be fused into
a mass.

2. Gold is of a fine light yellow colour ; its
hardness is scarcely superior to that of tin. Its
specific gravity is about 19.277, audit is some-
what increased by hammering. In malleability
and ductility it is superior to all the other
metals. It has a considerable degree of tenacity ;
a wire of 0.078 inch in diameter will support

[ 447 ]

a weight of l50lbs. It fuses at about 1300
Fahreoheit. It is not altered by exposure to
air or water.

3. There are no accurate experiments re*
corded on the combinations of gold with oxy-
gene. A purple oxide is formed when gold
leaf is burnt by electricity, or gold wires by
the Voltaic battery, but its composition has not
been ascertained. No deoendance can be put
on the statements of chemists relative to pure
oxides of gold, said to be obtained by treating
solution of gold, with potassa, lime, and other
substances, for in these instances, as far as ray
experience has gone, triple compounds always
appear to be formed.

4. Gold combines with chlorine when the
metal, in a minute state of division, is heated in
chlorine, or when the nitro-muriate of gold is
part'ally decomposed by heat, treated with
muriatic acid and evaporated to dryness. It
is a brown substance, is very deliquescent, and
readily decomposes the water in the atmosphere,
forming a muriate of gold. It has not been
examined with precision.

5. There are no known combinations of gold
with hydrogtne, azote, carbon or boron.

6 There has been no distinct combination
made of gold and sulphur.

7. Gold combines with phosphorus: this

[448]

compound ha^been recently made in the labora-
tory of the Royal Institution by Mr. E. Davy,
by heating gold, in a minute state of division,
with phosphorus in an exhausted tube. It is
of a gray colour, and has the metallic lustre.
It is readily decomposed by the heat of a spirit
lamp; and contains about I4 per cent, of phos-
phorus.

8. The metals of the alkalies combine with
gold; but the alloys have not been minutely
examined.

9. Gold forms alloys with the other metals ;
many of them are brittle, as those of bismuth,
antimony, and lead. Others are malleable, as
those of silver, copper, and platina, The alloy
of gold and copper is employed in coin.

The applications of gold to the useful and
ornamental arts, 8cc. are too well known to
need particular delail. The purple oxide of
gold is employed for colouring glass and por-
celain.

36. Platinum,

1. The ores of platinum are very rare ; they
have been found only in South America and in
Spain. The ores from South America consist
of small roundish flattened grains. The ore
found in Spain is in a vein principally consist-
ing of silver. The only places ia South America

L 449 ]

in which grains of the ore of platlna have been,
discovered are at Choco in Peru, Santa Fe near
Carthagena, and a district in the Brazils.

Plalinum is procuredfrora the South American
ore by dissolving it in aqua regia, and dropping
into it a solution of sal-ammoniac; a yellow
powder fall^ down, which must be redissolved
in nitromuriatic acid, and again precipitated by
sal-ammoniac; and after this second process,
when ignited to whiteness, it is pure platinum.
The particles may be made to unite into one
mass by hammering them in a state of ignition,

2. Platinum was first described as a peculiar
metal by Dr. Lewis, in 1754.

Platinum is of a white colour, but much less
brilliant than silver; it is not quite so hard as
malleable iron: its specific gravity after being-
hammered is 21,3, that of water being 1. It is
very ductile, and malleable; may be easily drawn
into wires about the -^^^ of an inch in diameter^
and hammered into very thin plates : its tenacity
is such, that a wire 0.078 of an inch in diameter
is capable of supporting a weight of 274. 3 libs,
avoirdupois without breaking. It is not fusible
by the heat of a forge; and requires either the
intense heat of the concentrated solar rays, of
Voltaic electricity, or of a flame produced by
the agency of oxygene gas.

3. Platinum combines with oxygene only
VOL. I. G g

[ 450 ]

with great clifEculty. When intensely ignited
by Voltaic electricity it fuses, and throws off
sparks, and a fume rises from it, which is pro-
bably the oxide of platinum.

When solutions of platinum are precipitated
by alkalies, or alkaline earths, the precipitate
always appears to be a compound of platinum,
oxygene, and the earth or alkali employed;
yet Mr. Chenevixhas stated, that by dissolving
the precipitate from the nitromuriatic solution
by lime water in nitric acid, and driving off the
acid by heat, a brown powder is formed, which
is an oxide of platinum, and which contains I3
per cent, of oxygene. The same ingenious
chemist stales that there is another oxide of
platinum of a green colour, made by healing
the brown oxide, and which he believes contains
7 per cent, of oxygene. I have seen several
experiments made by Mr. E. Davy, in which no
precipitate was produced by the action of lime
water on the nitromuriatic solution : the lime
water was used in various proportions, but
without success.

When an alloy of potassium and platinum
is heated, exposed to air, both metals burn, and
a yellow powder is formed, which gives off
oxygene gas by ignition ; but this powder, after
being long washed, reddens turmeric, so that
it is not pure oxide of platinum.

[ 451 ]

4. A bright brown powder may be obtained
by evaporating to dryness the nitromuriatic
solution of platinum. This powder, when
heated to whiteness, is resolved into platinum
and chlorine, and the chlorine gas may be col-
lected in a proper apparatus. From some ex-
periments made on this powder, at my request,
by Mr. E. Davy, it appears to contain about
18. 5 per cent, of chlorine; but this esliraate
can be considered only as an approximation,
for there are many difficulties in gaining accu-
rate results on a substance so easily decomposed.

5. Sulphur combines with platinum when
they are heated together in exhausted tubes.
The sulphuret is an infusible black powder, de-
composable by a white heat. According to
Mr. E. Davy, who first made it in the laboratory
of the Royal Institution, it contains about 16
per cent, of sulphur. He supposes that there
is another combination of sulphur and platina,
which may be made by heating the precipitatie
from the nitromuriatic solution by sal-ammoniac
and sulphur together, and which contains 28
per cent, of sulphur.

6. Phosphorus and platinum combine with
great energy, when the phosphorus is made to
act in vapour, in exhausted tubes, on platina,
heated to dull redness; the combination is so
violent that the mass becomes vividly ignited.

[ 452 ]

The phosphoret oFplatina is an infusible blueisfi
gray powder with little lustre. According td
Mr. E. Davy, it contains more than 17 per cent,
of phosphorus. He believes that there is a
superphosphorei of platina containing 30 per
cent, of phosphorus, made by heating the yel-
low powder procured by sal-ammoniac with
phosphorus; but new experiments are wanting
on this result, as well as on the results of the
action of sulphur on platinum. The quantities
do not correspond with the theory of definite
proportions ; and as neither the metal nor the
compounds made can be fused under the cir-
cumstances of the experiment, it is not possible
to say that the combination is perfect ; and as ail
such combinations are decomposable by a strong
heat, part of the compound first formed may
be decomposed before other parts of the mass
enter into union.

7. From the experiments of M. Descotils it
is probable that platinum is capable of combin-
ing with boron; it has never been united to
hydrogene, azote, or carbon.

8. Platinum readily unites to potassium and
sodium; their combination takes place with
ignition, and a bright brittle mass is obtainedj
from which the alkaline metals are readily sepa-
rated by the action of air or water. Plati-
imm combines with most of the other metals;

I 453 ]

but the properties oF its alloys have been very-
little studied. To the fusible metals it cominuni-
cates difficult fusibility. It amalgamates with
mercury when heated with that metal in a finely
divided state. It combines with gold, and ren-
ders its colour pale ; even — of platinum can
be detected in union in gold, from the colour.

9. Platinum is a most valuable metal; as it is
notoxidable, nor fusible under common circum-
stances, and only difficultly combinable with
sulphur, and not acted upon by common acids,
it is admirably adapted for the uses of the philo-
sophical chemist, and may be advantageously
employed in all cases where gold is applied,
unless the use is connected with the colour or
malleability of the metaL The general applica-
tion of platinum as a manufactured metal to
the purposes of the laboratory is one of the many
benefits which chemistry and the useful arts owe
to Dr. WoUaston.

37. Arsenic or Arsenicum.

1. Arsenic may be easily procured by heat-
ing tlie substance knovvn by the name of white
arsenic in powder with charcoal, in a Florence
flask, or a glass tube ; before the mixture be^
comes red hot, a metal sublimes, and condenses
in tile upper part of the vessel, which is arsenic.

%. Arsenic is of a blueish white colour, not

[ 454 ]

unlike that of steel. Its specific gravity is
8.51. It is very brittle: its point of fusion has
not been ascertained ; but it is the most volatile
of all the metals, rising in vapour at about 356*
of Fahrenheit's scale. When a part of it is sud-
denly ignited, it burns with a pale blueish light,
sending off dense white fumes. It burns spon-
taneously in chlorine.

3. There are two known combinations of
arsenic and oxygene ; both of which are pos-
sessed of several of the properties of acids.
The first is the substance formed by combustion,
and this contains the smallest quantity of oxy-
gene ; the compound containing the largest
quantity of oxygene may be formed by distill-
ing nitrous acid, mixed with -Jg- of its weight
of muriatic acid from the other compound.
The compound formed by combustion has been
called arsenious acid, and likewise white oxide
of arsenic. When procured by precipitation
from acid solutions, it exists as a Ivydrat : it is
fusible by a strong heat suddenly applied, but
sublimes slowly at 3S3 Fahrenheit; after fusion
it appears as a white vitreous substance, of
specific gravity 5. It is soluble in 80 parts of
water at 60°, and in 15 parts at 212°. Its taste
is acrid, leaving an impression of sweetness.
Wiien heated its smell is like that of garlic.
-The compound of arsenic with the largest pro-

[ 455 j

portion of oxygene is called arsenic acid. It
is much more fixed in the fire than arsenious
acid, is very soluble in water, and has an intense
sour taste. From experiments on the quantity
of oxygene absorbed by arsenic during its con-
version into these two compounds, made by
Proust and by myself, I conclude that the arseni-
ous acid consists of about 25 of oxygene, and 75
of metal ; and the arsenic acid of 33 of oxygene
and 67 of metal. Hence it appears that the
quantity of metal being the same, the oxygene in
the arsenic acid is to that in the arsenious nearly
as 3 to 2 ; and if the arsenious acid be supposed
to contain two proportions of oxygene, the
number representing arsenic will be 90; and
those representing arseoious and arsenic acids
will be 120 and 135.

4. The only compound of chlorine and
arsenic known, is made by the combustion of
the metal in chlorine, or by distilling a mixture
of arsenic and corrosive sublimate together : it
is a heavy limpid fluid, capable of being easily
rendered gaseous, forming a liquid muriate of
arsenic by the action of a small quantity oFwater,
and affording a precipitate of arsenious nearly
acid by the action of a large quantity. From
my experiments it appears that the compound
of chlorine and arsenic, which may be called
arsenicane^ consists of AO melal to 60 of chlorine ;

[ 456 ]

tlierefore it may be regarded as composed of
two proportions of chlorine, and one of metal.

5. Arssnic combines with hydrogene. The
best known substance containing the two bodies
is arseniuretted hydregene gas. This elastic
fluid, which was discovered by Scheele, may be
procured by dissolving an alloy of 14 parts of
tin and 1 of arsenic in muriatic acid. This
substance has an extremely fetid smell ; it burns
when brought near an inflamed taper in the
atmosphere; its flame is blue; and if the vessel
in which it is burnt have a narrow neck, it de-
posits arsenic. It inflames spontaneously when
acted upon by chlorine : it is soluble only to a
very slight extent in M'ater. It is probable that
the gas called arseniuretted hydrogene is always
a mixture of a true gaseous compound of arsenic
and hydrogene, with common hydrogene. Its
specific gravity varies, as I have found, from
5 to 8, that of hydrogene being 1. When
decomposed by attracting the arsenic from it,
by the action of ignited metals, there is an ex-
pansion of volume. M.Gay Lussacand Thenard
lound 100 parts of it decomposed by tin be-
come 140 parts. M. Stromeyer states that he
analysed a gas consisting of 106 parts arsenic,
and 2.19 hydrogene. This would agree with
the idea that the pure gas is composed of 2 pro-
portions of hydrogene, and one of metal ; hut

[ 457 1

"such a gas must be more than twice as heavy as
any specimen that has been weighed ; and this
circumstance leads me to doubt of the correct-i
ness of M. Stromeyer's results.

There is likewise a solid compound of hy«
drogene and arsenic : it may be procured by
acting on water by an alloy of potassium and
arsenic in great excess : it is a brown powder,
which burns, when gently heated in the atmos-
phere, and which gives off arseniuretted hy-
drogene, when heated in close vessels. The
same substance is procured when arsenic is
made the negative surface in contact with water
in Voltaic combinations. No experiments have
as yet been made on the proportions of its ele-
ments.

6. Sulphur and arsenic readily unite by fusion,
and form a red vitreous semitransparent mass^
The same substance is found native in different
parts of Europe, and is called realgar; it is often
crystallized in transparent prisms: its specific
gravity is 3.225. If Thenard's account of its
composition be considered as accurate, it must
consist of two proportions of arsenic, and three
of sulphur, 180 and 90. If sulphuretted hy-
drogene gas be made to act upon a solution of
arsenious acid in muriatic acid, a fine yellow
powder falls to the bottom. This powder is
usually called oi'phnent. It may be formed like-

[ 458 ]

%vise by subliming arsenic and sulphur together
in a heat not sufficient to produce a fusion of
the mass. It is composed of thin plates, which
have a considerable degree of flexibility. Ac-
cording to Thenard it contains more sulphur
than realgar ; but Mr. Proust states that by
fusion it becomes realgar.

7. Arsenic readily combines with phospho-
rus, and they form together a black powder j
the proportions of its elements have not yet
been accurately ascertained.

8. Arsenic has not been combined with azote,
boron or carbon.

9. Arsenic combines with most metallic
substances. It renders the metals of the fixed
alkalies less fusible by uniting to them, but its
alloys with the common metals are usually very
fusible. It renders gold and platina brittle,
and gives whiteness to copper : none of the
alloys containing it in any considerable quantity
are malleable,

10. Arsenic is not much used in the arts*
Realgar and orpiment are employed as pig-
ments. The solutions containing arsenious, or
arsenic acids, are extremely poisonous. The
arsenious acid in very small doses, has been
employed in medicine, particularly for the
cure of intermittent fevers.

[ 459 ]

38. Molfhdenum.

1. There is an ore found in different parts of
Europe, particularly in Sweden, not unlike
plumbago, from which Scheele, in 1778, pro-
cured a white powder; and from this powder,
Hielm, in 1782, obtained a metal, which he
called molybdenum.

Pure molybdenum may be obtained either
from the ore like plumbago, or from another
ore found in Carinthia, called the molybdat of
lead ; by digesting them in powder in nitric
acid, and boiling the mass in sulphuric acid ;
by lixiviation with water a liquor is obtained,
which v/hen acted on by solution of ammonia
passed through a filter and mixed with nitric
acid deposits a white powder, and this powder
intensely ignited in a charcoal crucible mixed
with linseed oil affords the metal.

2. Molybdenum, according to the observa-
tions of Bucholz, is brittle ; its specific gravity is
8.6l 1. Its colour is white It burns when placed
on ignited charcoal and acted on by a current
ofoxygene gas, and gives off a white smoke
which collects in small needle-formed crystals.

3. There are two well defined combinations
of molybdenum and oxygene. One is blue,
the other is pale yellow ; they both possess acid
properties, and therefore may be distinguished
by the names nudybdous and molybdic acids.

[ 460 ]

The moljhdic acid is easily obtained from the
ores of the metal by treatment with acids
3nd ammonia : the white powder described in
the last page is this substance combined with
water, and it may be procured pure by ignition.
Its specific gravity is 3.4 ; its taste is sour ; it is
fusible in a strong heat, and volatilized by in-
tense ignition : it is soluble in about 1000 times
its weio-ht of water.

The blue acid, or the molybdous acid, is formed
by triturating together in boiling water, one
part of molybdenum in powder, and two
parts of molybdic acid. The solution is to be
p^issed through a iiltre, and evaporated in a
temperature not exceeding 120 ; the blue acid
remains in the state of a fine powder. This
acid is more soluble in water than the molybdic
scid, andactsmore intensely on vegetable blues,
converting them to red. According to Bucholz
the blue acid consists of 100 parts of metal to
34 of oxygene, and the yellow acid of 100 parts
of metal to 50 of oxygene. On these data it
seems probable that moiybdous acid consists of
2 proportions of oxygene and one of metal;
and molybdic acid of 3 proportions of oxygene
and 1 of m.etal; and assuming the composition
the molybdous acid as the foundation of cal-
culation, the number representing molybdenum
will be 88.2. Mr. Bucholz supposes that there

[ 461 ]

are oxides of molybdenum, containing smaller
quantities of oxygene than the two acids. It iS
probable that there is a brown oxide containing
a single proportion of oxygene obtained by ex-
posing the metal to a red heat ; but what Buchol^;
considers as a violet brown oxide produced by
heating the brown oxide, is probably only a
mixture of the brown oxide and the blue acid.

4. No direct experiments have, I believe, been
made on the action of clilorine on molybdenum ;
but when the molybdic acid is dissolved in
muriatic acid, and the residue heated to redness,
chlorine rises, and the blue acid remains behind ;
but a grayish sublimate is likewise formed, ia'
which chlorine is indicated by the action of
nitrat of silver.

5. Molybdenum combines readily with sul-
phur by fusion, or by heating strongly together
molybdic acid and sulphur. The sulphuret of
molybdenum is a black shining powder, the
same as the native mineral from which Scheele
first procured the acid. According to Bucholz it
contains 60 of metal and 40 of sulphur per
cent, and therefore may be considered as con-
sisting of one proportion of metal and two of
sulphur.

6. Phosphorus combines with molybdenum ;
but the properties and constitution of the phos'
ptioret have not been investigated.

t 462 ]

7. Hydrogene, azote, carbon, and boron,
have not been combined with molybdenum.

8. It unites to several of the metals ; one
of the most perfect of its alloys is with iron.
With lead it forms an alloy somewhat mal-
leable. Most of its other alloys break under
the hammer; from the diflBcuit fusibility of the
metal it is not easy to make them uniform in
their constitution.

Molybdenum has not yet been applied to
any of the purposes of the arts.

39. Chromium,

1. There are two ores from which chromium
may be procured ; one is the read lead ore of
Siberia, the cbromat of lead, the other is the
chromat of iron, which has been found in
France and in North America.

Chromium was discovered by Vauquelin, in
1797. To obtain chromium, chromat of lead
in fine powder is to be digested with moderately
strong muriatic acid, till its power of action is
exhausted. The fluid produced is to be passed
through a fillre, and a little oxide of silver, such
as is procured by precipitation from nitric acid
by potassa, very gradually added to it till the
whole solution becomes of a red tint. This
liquor by slow evaporation deposits small ruby

t 463 ]

red crystals, which, when intensely ignited,
mixed with a little charcoal powder, afFord
chromium. Chromat of lead may be procured
from chromat of iron, by decomposing it by
liydrat of potassa, making a solution in nitric
acid, and adding solution of nitrate of lead ;
the chromat of lead falls down as a beaiitifiat
orange powder.

Chromium is a white brittle metal, requir-
ing an intense heat for its fusion ; it is very dif-
ficultly acted on by acids. It does not readily
enter into combustion. Its specific gravity is
5.9.

3. Very few experiments have been made ©n
the combinations of chromium. The red crys-
tals procured from chromate of lead by muriatic
acid appear to be a hydrated acid; they are
soluble in water, have a sour taste, and coiii-
bine with alkalies.

The red crystals strongly heated become a
green powder, which is considered as an oxids
of chTOmium. It is said that from 100 parts of
the red crystals 6/ parts of metal may be pro«
cured. The acid of chromium, when combined
with alkalies, precipitates most of the metallic
solutions. In solutions of mercury it produces
a vermilion red precipitate ; in those of silver, a
carmine red ; in those of tin, a green. The name

[ 464 ]

chromium has been given to the metal from its
remarkable colouring powers.*

4. The artificial chromate of lead forms a
beautiful and permanent pigment. I have found
the orange colour most pure when the nitrate
of lead used for the precipitation contained an
excess of acid. The oxide of chromium has been
employed for giving an emerald green colour
to glass and enamel. Chromic acid is the colour-
ing matter of the spinelie ruby; and oxide of
chromium gives its beautiful colour to the
emerald. The oxide of chromium has been
lately found in some meteoric stones

* From Xfft)/A«.

[ 465 ]

DIVISION VI.

OF SOME SUBSTANCES, THE NATURE OF
WHICH IS NOT YET CERTAINLY KNOWN.

1. Preliminary Observations,

The bodies to be examined in this division
have been arranged into a distinct class, because
they present some extraordinary and anoma-
lous results, and because as yet the knowledge
obtained respecting their nature is imper-
fect ; many of the facts ascertained respecting
them harmonize with the general doctrines of
the science, and some of them offer new views
respecting the arrangements and properties of
matter ; they are therefore amongst the most
interesting objects of chemical enquiry.

2. Of the Fluoric Principle,

1. There is a substance found abundantly in
nature called jluor spar, it is usually either blue
green, yellow, or white, transparent, and crys-
tallized in cubes. It is a common product of
the mines in Derbyshire.

2. When this substance, in fine powder, is
mixed with oil of vitriol and distilled in retorts

VOL, I, Hh

I

[ 466 ]

of Sliver or lead, connected with receivers of
the same metal artificially cooled ; an intensely-
active fluid is produced. It has the appearance
of sulphuric acid, but is much more vola-
tile, and sends olF white fumes when exposed to
air. It must be examined with great caution, for
when applied to the skin it instantly disorganizes
it, and produces very painful wounds. When
potassium is introduced into it, it acts with
intense energy upon it, and produces hydro-
gene gas, and a neutral salt : when lime is made
to act upon it there is a violent heat produced,
water is given off, and the same substance as
fluor spar is produced. When it is dropped
into water a hissing noise is produced with much
heat, and an acid fluid not disagreeable to the
taste is formed if the water be in sufficient
quantity. It instantly corrodes and dissolves
glass

3. Ifj instead of being distilled in metallic
vessels, the mixture of fluor spar and oil of
vitriol be distilled in glass vessels, little of the
corrosive liquid will be obtained; but the glass
wall be acted upon, and a peculiar gaseous sub-
stance will be produced, which must be col-
lected over mercury. The best mode of pro-
curing this gaseous body is to mix the fluor
spar with powdered glass or powdered quartz,
and in this case the retort may be preserved

[ 467 ]

From corrosion, and the gas obtained in greater
quantities. This gas, which is called silicated
fluoric gas^ is possessed of very extraordinary-
properties.

It is very heavy ; 100 cubical inches of it
weigh 110.77 grains, and hence its specific
gravity is to that of hydrogene nearly as 48 to
J. When it is brought in contact with water it
instantly deposits a white gelatinous substance,-
which is hydrat of silica, and the water becomes
an acid solution of silica ; it produces white
fumes when suffered to pass into the atmosphere.
It is not affected by any of the common com-
bustible bodies, but when potassium is strongly
heated in it, it takes fire and burns with a deep
red light ; the gas is absorbed, and a fawn
coloured substance is formed, which yields
alkali to water with slight effervescence, and
contains a combustible body, and the washings
afford potassaand a salt, from which the strong
acid fluid mentioned in the last section may
be procured by sulphuric acid.

4. If instead of glass or silica the fluor spar
be mixed with dry vitreous boracic acid, and dis-
tilled in a glass vessel with sulphuric acid, the
proportions being one part boracic acid, two
fluor spar, and 12 oil of vitriol % the gaseous sub-
stance formed is of a different kind, and is called
the Jluoboric gas. 100 cubical inches of it weigh

[ 468 ]

73.5 grains, so that its specific gravity is rather
more than 32 times that of hydrogene. Wlien
a little of it is suffered to pass into the atmos-
phere it produces fumes much more dense than
those produced by the gas described in the last
section, and which appear white, and almost
opaque. It is absorbed rapidly by water, and
forms with it a dense fluid like sulphuric acid
in appearance and consistence; and when water
is saturated with it at 50° Fahrenheit, it contains
700 times its volume of gas, and is of specific
gravity 1.7 7. When potassium is heated in
this gas, it takes fire, and burns with a red light ;
the gas is destroyed, if the metal be in suffi-
eient quantity, and an olive coloured substance
is produced, which seems to be principally
boron, and a neutral salt, which by the action
of oil of vitriol, affords the dense fluoric acid,
and sulphat of soda.

5. It appears extremely probable, from all
the facts known respecting the fluoric combina-
tions, that fluor spar contains a peculiar acid
matter; and that this acid matter is united to
lime in the spar seems evident from the circum-
stance that gypsum, or sulphate of lime, is
the residuum of the distillation of fluor spar
and sulphuric acid: the results of experiments
on the decomposition of fluor spar, have been
differently stated by different chemists ; the

[ 469 ]

maximum of sulphate of lime obtained from 100
grains in some experiments made in the labora-
tory of the Royal Institution, was 174.2 grains,;
and from this result fiuor spar may be supposed
to consist of 55 lime, and about 20.7 fluoric acid,
and this last number will represent the acid-

6. The dense acid fluid described in 2 must,
on the same idea, be supposed to be a compound
of an acid unknown in a separate state, and
water; and may be called hfdrojluoric acid;
and supposing all the water in oil of vitriol
transferred to it, it will consist of ^0.7 fluoric
acid, and 17 water.

7. The gas formed by the action of hydro-
sulphuric acid on a mixture containing silica and
fluor spar, silicated fluoric gas must be regarded
as a kind of neutrosaline gaseous compound
consisting of fluoric acid and silica, and it has
been found to afford, when decomposed by so-
lutions of ammonia, 61.4 per cent, of silica;
it may therefore be supposed to consist of
two proportions of acid 41.4, and one of silica
61. According to this view of its compo-
sition, the number representing it is about
102 ; 1 volume ©f it condenses two volumes of
ammonia, and they form together a peculiar
saline substance which is decomposed by water.
The composition of this salt is easily recon-
ciled to the numbers above given, as represent-
ing silica and fluoric acid, on the supposition

[ 470 ]

that it contains one proportion of ammoma,
and one of silicated fluoric acid ; and calculating
the number of silicated fluoric acid on this sup-
position it would be about 99.

There is great reason to believe that, when
potassium burns in this gas, it is the acid matter
which is decomposed, and that it consists of
oxygene united to an inflammable basis ; for if
it were the silica alone which is decomposed, or
if a mere combination were formed between the
potassium and the acid gas, the same quantity of
fluate of lime or fluor spar ought to be formed
from equal quantities of silicated fluoric acid,
acted upon by potassium, and afterwards ex-
posed to solution of ammonia, and the other
absorbed by water, and acted on by solution of
ammonia ; which I have found is not the case, for
in the first instance there is considerably less
produced. In the experiment, it seems likely
that the potassium acquires oxygene principally
from acid matter combined with the silica, and
that the inflammable basis of the acid partly
combines with the potassa, and partly with the
silica, or with silicum ; and forms with the first
a compound that eflervesces, and is partly de-
composed by water; and with the second an
insoluble substance, which affords silicated fluO'
ric acid by absorption of Oxygene.

8. It is extremely likely that fluoboric acid
gas is composed of the peculiar acid which is

[ 471 ]

supposed to consist of oxygene and an inflam-
mable basis, and boracic acid; but it appears
that in the combustion of potassium in this gas
it is the boracic acid alone that is decomposed,
and that the fluoric acid combines with the
potassa formed.

9. It is a peculiar circumstance with respect
to the fluoric principle, that silicated fluoric gas,
and fluoboric gas combine with bodies without
decomposition. Thus they both form peculiar
compounds with the alkalies ; and though silica
is deposited by the action of silicated fluoric
gas on water, and on other oxidated bodies, yet
the new compound formed always appears to
contain part of the earth, which is supposed to
be a constituent of the gas. In general, silica
and boracic acid can only be procured from the
two gases by the intervention of bodies that
contain water or oxygene : this circumstance,
if it were not opposed by the results of the ex-
periments on the action of potassium on silicated
fluoric gas, which, however, ought to be repeated,
might lead to the suspicion, that the fluoric {>;ases
are compounds of a principle unknown in the
separate state, but analogous to chlorine, with
silicum and boron ; that the hydrofluoric acid
is a compound of the same principle with
hydrogene and water, and Huor spar a com-
pound of the same principle with calcium.

[ 472 ]

10. If 50.7 be really the number representing
fluoric acid, it can be supposed to contain only-
one proportion of oxygene, and the fluoric
basis will be represented by 5.7) and it will be
the only known acid so constituted.

11. Silicated fluoric gas, when absorbed by
water, affords an acid fluid, which, when acted
upon by ammonia, deposits silica; and in glass
vessels pure hydrofluoric acid cannotbe obtained.
Silicated fluoric gas seems to form only one
combination with ammonia, which deposits
silica by the action of water; but fluoboric gas
forms three combinations with ammonia, one
volume of it condenses 1.2 and 3 volumes of
ammonia. The saline compound containing
the least quantity of ammonia is solid, the other
two compounds are fluids at the common tem-
perature of the atmosphere.

12. The only use to which the fluoric com-
binations have as yet been applied is for etching
on glass; for this pupose the hydrofluoric acid,
or the fluate of ammonia, should be used ; the
gasses have no action on glass.

13. Silicated fluoric gas, and diluted hydro-
fluoric acid were discovered by Scheele, in 1771.
Margraaf, three years before, had pointed out
some of the results of the action of acids on
fiuor spar; concentrated hydrofluoric acid, and
fluoboric gas were made known by some ela-

V

[ 473 ]

borate researches of Gay Lussac and Thenard,
in 1 809. My brother, Mr. John Davy, in 1810
and 1811, extended the knowledge of the
properties of these bodies, and the modes of
procuring them pure, ascertained the specific
gravity of fluoboric and silicated fluoric gasses,
and the proportions in their ammoniacal com-
binations. The action of potassium on silicated
fluoric gas, and fluoboric gas was investigated by
M. M. Gay Lussac and Thenard, in 1809; and
I made a number of experiments on the same
subject about the same time.

3. Of the Amalgam procured from ammomacal

Compounds.

1. When a globule of pure mercury is ne-
gatively electrified by a Voltaic apparatus of
100 pair of plates, it being in contact with
solution of ammonia in a cavity made in a piece
of muriate of ammonia, or any ammoniacal salt,
moistened in such a manner, and. so placed on
a disc of platina, that the circuit is completed ;
the globule rapidly increases in volume, the
quicksilver loses its fluidity, and at length be>-
comes of the consistence of soft butter, and
arborescent crystallizations shoot from it, which
are quite solid. The amalgam so formed has
perfectly metallic characters. It efTervesces copi-
ously when throv/n into v/ater, hy'drogene gas
is given off, and a solution of ammonia is found

[ 474 ]

in the water. When exposed to the air it gra-
dually loses its consistence ; it emits a strong
odour of ammonia, and reddens paper tinged
with turmeric held above it; and at last is found
merely quicksilver.

This curious experiment was made about
' the same time by Dr. Zeebeck of Jena, and by
M. Kissinger and Berzelius of Stockholm,
before the middle of the year 18o8 ; and- they
were led to make it in consequence of my ex-
periments on potassa and soda.

£. I found a still more easy mode of making
the amalgam by employing mercury combined
with a minute quantity of potassium, sodium,
or barium. When a compound of this kind is
placed in contact with a solution of ammonia, or
any moistenedammoniacal salt, it enlarges toeiffht
or ten times its bulk, and becomes a soft solid,
and may be preserved for a much longer time
than the amalgam formed by electrical powers ;
it changes very slowly even under water.

3. Different opinions have been formed, and
may still be formed, concerning the nature of
this extraordinary substance. M. Berzelius
supposes that ammonia consists of a peculiar
metal combined with oxygene, and of which
metal hydrogene and azote are both peculiar
oxides ; this idea was one tlsat I started likewise
soon after the discovery of the amalgam.

4. Another view of the subject is, that the

[ 475 ]

amalgam consists of mercury united to azote
and liydrogenp, the hydrogene being in larger
proportion than in ammonia ; and this view has
been embraced and defended by M. M. Gay
Lussac and Thenard ; but the subject is still
obscure and mysterious, and the true theory of
the experiment can only be developed in con-
sequence of new facts.

5. Soon after the discovery of the amalgam,
I attempted to procure a peculiar metallic sub-
stance from it by distillation out of the contact
of air, but without success ; whether I used the
amalgam formed by electricity, or that procured
by the intervention of the alkaline metals ;
on the application of heat, hydrogene and am-
monia were always evolved, and the mercury
recovered its former state. On the idea of the
basis of ammonia being a peculiar metal, oF
which azote and hydrogene are oxides, these
results can only be explained by supposing that
the amalgam being formed from moist substances,
sufficient water adheres to it, to afibrd oxygene,
and to produce the gaseous matter; and the
most perfect amalgam does not yield a quantity
of gaseous matter equal to more than -^-^ of its
weight.

I procured ammonia and hydrogene by heat-
ing the amalgam, however in cases in which it
was carefully wiped with bibulous paper, and

[ 476 1

in which there was no appearance of adhering
moisture ; and similar results have been ob-
tained by M. M. Gay Lussac and Thenard.

In the most accurate experiments the propor-
tions of ammonia and hydrogene were two to
©ne in volume.

6. There is no instance known of mercury
retaining its metallic characters in combination
with any other substance than a metal ; and it
seems very probable that, if the matter existing
in the amalgam from ammonia could be pro-
cured in its perfect form, and could be exhibited
as a solid under pressure, and at a very low
temperature, it would appear as an extremely
light metallic substance. On the idea of its
being a compound of azote and hydrogene it
will consist of one proportion of azote 26, and
§ of hydrogene 8 ; and the number represent-
ing it will be 34.

It is very difficult, but not however altoge-
ther impossible to reconcile the idea of the sub-
stance in the amalgam being elementary, with
analogies belonging to the general series of
, definite proportions. On such a supposition
azote must necessarily contain more than four
times as much oxygene as hydrogene ; and if
1 of basis to 5 of oxygene, be supposed in hy-
drogene, then there will be 1 to 25 in azote,
and 1 to 40 in nitrous oxide, 1 to 55 in nitrous

[ 477 ]

gas, 1 to 85 in nitrous acid, and 1 to IB in
ammonia; and 5, 15, 25, 40, 55, and 85, form
a series of numbers having definite relations to
each other.

If the hypothesis of the elementary nature of
the substance in the amalgam be adopted, water
must be supposed to be constituted by 1 basis,
and 50 of oxygene.

It is extremely unlikely that siich proportions
should exist, and the general tenor of our
knowledge of chemistry, as well as the results
of the experiments, render it much more pro-
bable that the amalgam is composed of quick-
silver, azote, and hydrogene.

[ 478 ]

DIVISION VII.

ON THE ANALOGIES BETWEEN THE UNDE-
COMPOUNDED SUBSTANCES; SPECULA-
TIONS RESPECTING THEIR NATURE; ON
THE MODES OF SEPARATING THEM, AND
ON THE RELATIONS OF THEIR COM-
POUNDS.

1. Of the Analogies between the undecompounded
Substances ; Ideas respecting their nature,

1. The undecompounded substances most
analogous to each other, are certainly to be
found amongst the metals ; some of these are
so similar that it requires refined observation,
and sometimes experiment to distinguish them.
There is likewise a chain of gradations of re-
semblance which may be traced thoughoul the
whole series of metallic bodies, at the same
time that certain similar and characteristic pro-
perties are found to belong to metals in other
respects most unlike each other.

Silver and palladium, antimony and tellu-
rium, agree in a great number of qualities. Pot-
assium and platinum, if we except their lustre,
colour, and power of conducting electricity, are
bodies extremely dissimilar ; yet, by arranging

[ 479 ]

the metals in the order of their natural resem-
blances, these two subtances may be made parts
of one chain of natural bodies: potassium,
sodium, and barium are very like each other ;
barium approaches to manganesum, zinc, iron,
tin, and antimony. Platinum is analogous to
gold, silver, and palladium ; and palladium
is connected by distinct analogies with tin,
zinc, iron, and manganesum. Arsenic and chro-
mium, though amongst the most dissimilar of
the metals in other respects, agree in the pro-
perty of forming acid matter by combination
with oxygene.

Amongst the inflammable bodies not metallic
there are analogies, but not a similar series. Sul-
phur and phosphorus agree in many respects ;
carbon and boron are likewise analogous, and
are connected by distinct relations with the
metallic substances. Azote, whilst it agrees
with the other combustible bodies that have been
named in forming an acid by saturation with
oxygene, is analogous to carbon in its incapacity
of uniting to chlorine.

Chlorine and oxygene are separated from the
inflammable bodies by a number of marked dis-
tinctions ; yet sulphur agrees with chlorine in
forming an acid by combining with hydrogene;
and has a weak attraction for chlorine and a
strong attraction for metallic substances.

I 480 ]

2, As far as our knowledge of the nature of
compound bodies has extended, analogy of pro-
perties is connected with analogy of compo-
sition; if one of the inflammable solids or metals
j[s proved to be compound, there would be
strong evidence for supposing that the others
.were likewise compounded. It has been already
.mentioned that sulphur and phosphorus, when
Voltaic electrical sparks are taken in them in a
state of fusion, afford hydrogene gas. 1 found
likewise that when an alloy of tellurium and pot-
assium was acted upon by melted sulphur,
telluretted and sulphuretted hydrogene equal
to at least 80 times the volume of the sulphur
were disengaged. I have made many experi-
ments of this kind with similar results, the sul-
iphur being recently sublimed in azote, and
moisture being excluded with the greatest care.
In the experiments of Voltaic electrization, it
might be supposed that the hydrogene being
only in very small quantity might belong to an
accidental admixture in the sulphur and the
phosphorus ; but the proportion is too large in
the experiments on the action of tellurium
potassium and sulphur, to allow of a similar
inference, and it seems more probable that it
arises either from the decomposition of the
sulphur, or of the metals, or all of these bodies.
3. We know nothing of the true elements

[ 4§I 1

belonging to nature; but as far as we canreasoli
from the relations of the properties of matter ;
hydrogeue is the substance which approaches
nearest to what the elements may be supposed
to be. It has energetic powers of combination^
its parts are highly repulsive as to each other,
and attractive of the particles of other mattefj
it enters into combination in a quantity very
much smaller than any other substance, and in
this respect it is approached by no known body.

After hydrogene oxygene partakes most of
the elementary character ; it has perhaps a
greater energy of attraction, and next to hydro-
gene is the body that enters into combination
in the smallest proportion.

4. I have already hinted at the idea that all in-
flammable matters may be similarly constituted,
and may contain hydrogene. And on this
suppositioil they may be conceived to owe their
powers of combining both with oxygene and
chlorine, to the attractive energies of their com*
bined hydrogene.

On the most probable view of the nature of
the amalgam from ammonia, as I have men-
tioned, it must be supposed to be composed of
hydrogene, azote, and quicksilver ; and it may
be regarded as a kind of type of the com-
position of the metals ; and by supposing them
and the inflammable bodies different combiria-

fOL. I. 1 i

[ 482 ]

tions of hydrogene with another principle as
yet unknown in the separate form ; all the phe-
nomena may be easily accounted for, and will
be found in harmony with the tlieory of definite
proportions.

The metal of ammonia or ammonium must he
supposed to be constituted by 8 of hydrogene,
and 26 of azote ; and as azote unites to five
proportions five times 15 of oxygene, it may
be supposed lo contain ten proporlions of
hydrogene; and its constitution may be thus
expressed, 10 proportions of hydrogene and 16
proportions of an unknown basis. Ammonium,
on the same hypothesis, will consist of 16 un-
known basis, and 18 hydrogene. Potassium,
the number representing which is 75 ; as it
combines with 3 proportions of oxygene, may /
be supposed to consist of 69 uiJknown basis,
and 6 hydrogene. Sodium, which is represented
by 88, and which likewise combines with three
proportions of oxygene, may be considered as
consisting ef 82 basis, and 6 hydrogene. Tin,
the number of which is 110, and which com-
bines with two proportions of oxgene may be
supposed to be constituted by I06 ofbasisand4
hydrogene ; and silver, which is represented by
£05, of 203 of basis, and 2 hydrogene. Amongst
the acidifiable bodies, sulphur, which is repre-
sented by 30, may be supposed to consist of

6 hydrogene, and 24 basis; Phosphorus of 4
hydrogene, and 16 basis ; and charcoal of 4
h) drogene and hi basis. It will be unnecessary
to supply any more of these estimations, the
principles of which are obvious ; and in an ele»
mentary book it would be improper to dwell
upon matters of mere speculation; even these
transient views have been developed merely for
the sake of pointing out a promising path of
enquiry.

5- In supposing the quantity of liydrogene in
the inflammable solids and metals denoted by
the quantity of oxygene or of chlorine they
absorb, it is taken for granted that the hydro-
gene forms only water or muriatic acid in the
new combination, but it is possible that hydro-
gene may combine with oxygene and chlorine
in many different proportions, and that its
union with a peculiar basis may modify its
power of attraction ; so that even allowing the
general hypothesis, no confidence can be placed
in the numerical expressions of the proportions
of hydrogene and basis ; they are offered merely
as possible circumstances.

6. The probabilities that the metals and in-
flammable sohds may be constituted by different
and various proportions of hydrogene and an
unknown basis, are however strengthened by

[ 4^ 1

the Fact, tliat the metals in which hydrogene is
supposed to be attracted by the largest quantity
of other matter are the least disposed to combine
with oxygene and chlorine ; and those that are
supposed to contain the largest quantity of hy-
drogene to the smallest quantity of other matter,
are the most combustible, and likewise those
supposed to contain the largest, and conse*
quently the least attracted quantity of hydro-
gene, have the lowest specific gravity.

7. When the analogy of the oxides to many of
the hydrats, and that of the combinations of chlo-
rine to many of the neutral salts, is considered,
bodies so much alike that till lately they have
been confounded together ; the view that the
inflammable bodies contain hydrogene becomes
still more likely. W ater cannot be separated
from the hydrats of potassa or soda by heat ;
and the hydrat of lime is extremely analogous
to the pure earth ; and supposing the oxides to
be compounds of unknown bases and water, it
might be expected that the water would adhere
to them with great energy, and would only be
separated in consequence of the bases entering
into a new combination.

Common salt is very analogous to sulphat of
■potassa and other bodies known to consist of
acid matter and alkaline matter ; and if sodinExi

[ 485 ]

consist of a basis combined with hydrogene, then
common salt may be considered as composed of
the same basis united to muriatic acid.

8. Chlorine and oxygene agree in many of
their characters ; but the weight of chlorine, its
colour, its absorbability by water are all in
favour of its being a compound. The number
representing chlorine is so high that it may in-
clude four proportions of oxygene ; and if this
body be supposed to consist of oxygene united
to an unknown basis, the analogy of the com-
binations of chlorine, both to the oxides and the
salts, might be easily explained. The evidences
in favour of such an idea of the constitution
of chlorine are, however, much inferior to those
which render it probable that the inflammable
solids contain hydrogene ; and this speculation
on the composition of chlorine must not be
confounded with the notion that chlorine is a
compound of oxygene and muriatic acid free
from water; for supposing a basis to exist in
chlorine, it does not follow thatit will be acid
in its nature. Th^ characteristic acid belonging
to the combinations of chlorine is formed by the
union of that body with hydrogene ; and sul-
phur likewise forms gn acid by combining with
hydrogene..

9. I have mentioned, page 172, that in the
electrization of a globule qf mercury in wat^r^.

I

[ 486 1

oxygene appears lo be combined wilU the metal,
and yet no hydrogene evolved. I have made a
number of experiments on this subject, and have
ascertained that, in the process described, oxide
is formed, without any apparent compensation
in the production of inflammable matter; nor
was I able to detect any combination into which
the hydrogene could have entered; so that these
experiments, as they now stand, would induce
the belief that water is the ponderable basis
of both oxygene and hydrogene, and that these
two forms of matter owe their peculiar proper-
ties either to the agency of imponderable sub-
stances, or to peculiar arrangements of the
particles of the same matter; but such a for-
midable conclusion as this must not be hastily
adopted, for in all other cases oxygene and
hydrogene appear as perfectly inconvertible
substances, and in no other instance can one be
procured from water without the correspondent
quantity of the other, or without some product
in which the other may be supposed to enter.
In all cases in which the circuit appears to be
interrupted, even this is the case. When the
linger is plunged in a glass of water connected
with a wire of platina positively electrified fi cm
the battery of £000 double plates of the Royal
Institution, oxygene is produced, and there is
no appearance gf hydrogene; but in this case

«

[ 4S7 ]r

the body is connected with a floor containing
moisture, ami at tlie extreme point of the moist
surrace, wliere it is in contact with a metallic
body, hyclrogene must be disengaged; and the
same chansjes occur if a circuit be made throusih
eight persons, their hands being in contact,
the two forasing the extremity of the chain,
having their fingers plunged in two glasses
connected by wires of platinum with the two
poles of the battery ; hydrogene is produced
from one wire, and oxygene from the other.
Till 1 ascertained that even acids, and alka-
lies could be attracted from a central vessel
in the Voltaic circuit to the two extremities of
the positive and negative metallic surfaces, it
appeared very mysterious that oxygene and
hydrogene should be separately produced in the
Voltaic electrization of water; but if it be pos-
sible for lime to be attracted through sulphuric
acid to the negative surface, it seems equally pos-
sible that hydrogene maybe attracted through
the moisture in a living body; or a series of
decompositions and recompositions may be
simultaneously produced throughout the whole
extent of the moist surface, by which, whilst a
particle of oxygene is produced atone extremity
of the chain, a particle of hydrogene is evolved
at ihe other.

10. There is, however, no impossibility in the

supposition that the same ponderable matter in
different electrical states, or in different arrange-
ments, may constitute substances chemically
different: there are parallel cases in the different
states in which bodies are found, connected with
their different relations to temperature. Thns
steam, ice, and water, are the same ponderable
matter; and certain quantities of ice and steam
mixed together produce ice-cold water. Even if
it should be ultimately found that oxygene and
hydrogene are the same matter in different
states of electricity, or that two or three elements
in different proportions constitute all bodies,
the great doctrines of chemistry, the theory of
definite proportions, and the specific attractions
of bodies must remain immutable; the causes
of the difference of form of the bodies supposed
to be elementary, if such a step were made,
must be ascertained, and the only change in
the science would be, that those substances now
considered as primary elements must be consi-
dered as secondary ; but the numbers representr
ing them would be the same, and they would
probably be all found to be produced by the
additions of mulljpies of some simple numbers
pr fractional parts,

1 1. That the forms of natural bodies may de-
pend upon different arrangements of the same
particles of matter has been a favourite h ypothesis

[ 489 I

advanced in the earliest era of physical research,
and often supported by the reasonings of the
ablest philosophers. This sublime chemical
speculation sanctioned by the authority of
Hooke, Newton, and Boscovich, must not be
confounded with the ideas advanced by the
alchemists concerning the convertibility of the
elements into each other. The possible trans-
mutation of metals has generally been reasoned
upon, not as a philosophical research, but as
an empirical process. Those who have asserted
the actual production of the precious metals
from other elements, or their decomposition,
or who have defended the chimera of the phi-
losopher's stone, have been either impostors, or
ynen deluded by impostors. In this age of
rational enquiry it will be useless to decry
the practices of the adepts, or to caution the
public against confounding the hypothetical
views respecting the elements founded upon
distinct analogies, with the dreams of alche-
mical visionaries, most of whom, as an author
of the last century justly observed, professed an
art without principles, the beginning 0/ which
was deceit, the progress delusion, and the end
poverty,

[ 490 ]

Ih Of ihe Analopies between ihe FroperUcs of ihe
primary Compounds, and on iheir Chemical
Eelations.

I. Ill those compounds, which contain the
same element combined with b^ses that resem-
ble each other, a very great degree of similarity
Blight be expected ; and it is found that a number
of secondary combinations are still more analo-
gous to each other than any of the undecora-
ponnded bodies. Ittriaalid glucina, baryta and
strontia, potassa and soda are instHDces of bodies
■which, as to many of their properties, might be
mistaken for each other; and a chain of anaioeiies
may be traced through ail the combinations of
infiaramable bodies and metals with chlorine,
oxygene, and each other. All the acids, alkaline
earths, alkalies, and combinations of chlorine in
their pure states at common temperatures are
nonconductors of electricity, by far the greater
number possess a certain degreeof transparency ;
in their combinations with each other they
display analogous results ; most of them form
liydrats; they render solid a certain quantity
of water, and are usually dissolved by a greater
quantity ; and even acids combine with each
other in consequence of the intermedium of
water, as is the case with the sulphureous and
nitrous acid gasses.

Libavius's liquor, or stannanea, is a limpid

[ 491 ]

fluid ; iF mixed with a certain proportion of
water it becomes a solid crystalline body. The
glacial oil of vitriol, and the hydrophespho-
tom acid are instances of oxidated bodies form-
ing crystalline solids with water.

2, The earths and the oxides which are inso-
luble in water still condense a certain quantity
of this fluid, and it gives a greater fusibility to
those which retain it with sufficient energy to
be submitted so a strong heat. All oxides and
earths obtained by precipitation from aqueous
solution, that I have examined, are hydrats,
and such of them, as I have carefully analyzed,
I find contain the water in definite proportions.
The combination of an earth, an alkali, or an
oxide, with water may be considered as amongst
its weakest combinations, for the water is ex-
pelled by carbonic acid. The expulsion of
water from the earths seems to be connected,
as I stated in page 73, with the contraction of
volume, which many of them undergo by ig-
Mition : the particles, when the water is driven
off, approach nearer to each other, and a great
contraction is the result, and probably some-
times a semi-fusion. This quality on which^
as it has been stated, the p) rometer of Wedg-
wood is founded, is elegantly exemplified in an
experiment I have lately made on the hydrat
4)f zircona. When this bpdy is heated, at the

t 492 ]

snotnent of the expulsion of the water, there is
so g;reat and rapid a contraction of the particles
of the earth, that they become incandescent in
the process; and, from being as soft as resin,
become sufficiently hard to scratch rock crystal,

3. In general those compounds of oxygene,
the bases of which combine with most energy,
likewise exert the greatest force of attraction on
each oiher ; suph, for instance, are the nietals of
the fixed alkalies in their relations to sulphur,
phosphorus, arsenic, and tellurium; and pot-r
assa and soda readily combine with the acids ©f
sulphur, phosphorus, and arsenic, and with the
oxide of tellurium.

4. No refined experiments have as yet been
made on the mutual action of these compounds
of chlorine and oxygene, which are capable of
co-existing ; but the salts called hyperoxymuri-
ates are substances in which chlorine and oxy-
gene exist combined with metals ; and the
facility with which they are decomposed de-
pends upon the tendency of the metal to unite to
chlorine, so as to form a binary compound, a
circunrtstance connected with the expulsion of
the oxygene. The hyperoxymuriate of potassa,
when it was first formed by Dr. Higgins, was
supposed by him to be a species of nitre, from
the similarity of its obvious properties : and it is
remarkable that its composition is the same as
that of nitre, except that in the first salt there

[ 493 i

is a proportion of chlorine^ and in the second
one of azote. Hyperoxy muriate of potassa
consists of 1 proportion of potassium 75, 6 of
oxygene 90, and 1 of chlorine 67. Nitre con-
sists of 1 of potassium 75, 6 of oxygene 90,
and 1 of as^ote 26. The combinations of am-
monia with the compounds of chlorine, offer
a class of curious bodies to the chemical en-
quirer, the properties of which have never
been investigated ; that formed by phosphorana,
and referred to page 291, is a most extraordinary
substance, and its elements are combined with
a degree of energy which renders it analogous
to a primary compound.

5. In the combinations of ammonia with acids
and oxides the hydrogene of the ammonia is
always in sonie definite proportion to the oxy-
"gene of the acid or oxide, so that water may be
formed by the decomposition of the compound |
this is obvious from the decomposition of the
fulminating ammoniacal metallic compounds.
If a solution of ammonia be poured into a solu-
tion of gold, a brown powder falls down, which
when washed and dried, explodes by a gentk
heat. I caused it to detonate in small quantities
in exhausted glass retorts, and I found that
the products were water, azote, and gold.

Fulminatitig silver is a compound in which
the elements seem to be in similar relations lo

i 494 ]

each other ; it was discovered hy M. Berthollet,
and may be made by dissolving the oxide of
silver, procured from the nitrous solution by
lime water in solution of ammonia at common
temperatures, and exposing the mixture to spon-
taneous evaporation ; black crystals form, which
must be examined with great caution, and only
in small quantities, as they explode by the mere
contact of a soft body.

6. The extensive class of bodies called neutral
salts are formed by the mutual action of acids,
and oxides, alkalies and earths ; and in general
thoseoxidated bodies that contain least oxygene,
are such as most readily enter into combination
with acids ; thus the peroxides generally are
either insoluble in acids, or require the abstrac-
tion of a portion of oxygene to become soluble;
and in general two inflammable bodies in coai-
bining with oxygene, unite to less than the added
sums oi the quantity they would separately com-
bine with to saturation. Many of the neutral
salts may be considered either as combinations
of peroxides with inflammable bases or as alka-
lies united to acids, or as peroxides united to
oxides; for instance, the compound formed from
sulphureous acid gas and potassa consists of pot-
assium and sulphur, with three proportions of
oxygene, and may be regarded as a compound
of peroxide of potassium and sulphur. Sulphate

[ 495 ]

of potassa contains four proportions of oxy*
gene, and might be regarded as a compound of
peroxide of potassium, and oxide of sulphur.
They are in fact all compounds of oxygene with
double bases ; and when one fixed alkali, or
earth, or oxide, separates another, it may be
supposed that the basis only is changed; tluis,
where hydrat of potassa separates lime from its
nitric solution, it may be conceived that the
potassium only takes the place of calcium. And
th at the oxygene and water of the hydrat of pot-
assa unite to this metal, and that the potassium
unites to the oxygene, nitrous acid and water
of the solution.

7. It is very easy to estimate the compositiofi
of any of the combinations of alkalies, earths, or
oxides with acids, by adding together the num-
bers representing their elements ; thus sulpljate
of soda is composed of 60 sulphur, 90 oxygene,
which make two proportions of sulphuric acid;
and 88 of sodium, and 30 of oxygene, whick
make one proportion of soda. Carbonate at
lead is composed of two proportions of carbonic
acid, equal to 82.8, two proportions of oxygene
SO, and one of lead 39S. Sulphate of kad is
composed of two proportions of sulphuric acid
150, two of oxygene 30, and one of lead 39^ :
§ulphate of nickel of two proportions of ?,iilphii-
ricacid I50, and one of Qxide of nickel 141; and

[496]

these proportions agree almost precisely with
the best analysis.

8. it appears that in the neutrosaline com-
pounds in which there is a perfect harmony be*
tween the proportions of the elements, the result
IS neutralization ; and in this case a crystal-
line compound, or an insoluble compound is
usually formed. Thus in the instances above
mentioned, in the sulphates of soda and lead; the
sulphur is a binary proportion, and the oxygene
a binary proportion, or a multiple of a binar y
proportion ; and in the carbonate of lead, the
carbon is a binary proportion, and the oxygene
a multiple of a binary proportion ; and to give
another instance, in the sulphate of barytes the
sulphur is a single proportion, and the oxygene
a single proportion, or a multiple.

When, on the contrary, there is a want of
harmony in the proportions, the excess either
of acid or basis seems to be shewn in the pro-
perties of the result ; and it is seldom a crys-
tallized body. Thus in the soluble red sulphat
of iron, the number of proportions of oxygene
in the oxide are three, and those of the sulphur
in the acid are four : and this body is strongly
acid and uncrystallizable.

C 4^7 ]

III. On the relative Attractions of the undecomposed
Substances for each other.

1. The attractions oF the undecompounded
substances vary with the temperature, probably,
chiefly in consequence of their different degrees
of volatility ; for although freedom of motion in
the parts of bodies wonderfully promotes com-
bination, yet the disposition in bodies to assume
the aeriform state at high temperatures, enables
decompositions to take place in an order which
would not be expected from the known agencies
of the substances under common circumstances.

2. The bodies that follow are arranged in the
order of their attractions for oxygene, at the
lowest temperature of visible ignition, after the
results of ray own observation. Potassium,
sodium, barium, boron, carbon, manganesura,
zinc, iron, tin, phosphorus, antimony, bismuth,
lead, sulphur, arsenic, tungstenum, azote, palla-
dium, mercury, silver, gold, platinum.

3. The attractions of bodies for chlorine follow
an order very different, though with some ex-
ceptions ; potassium, sodium, zinc, iron, lead,
Sliver, antimony, bismuth, phosphorus, copper,
sulphur, mercury, platinum, gold.

4. The attractions of the undecompounded
bodies for sulphur have not been determined
to any extent. Potassium and sodium seem to

VOL. I K k

[ 498 3

have the highest attraction of any substances:
then iron, copper^ antimony, palladium, lead,
and silver.

5. No bodies combine with phosphorus with
more energy than the metals of the fixed alkalies;
and after them platinum, zinc, antimony, and
sulphur, appear to have the stron^iest attractions ;
but no very definite knowledge has been as yet
obtained on the relations of the phosphurets.

6. The general phen imena of the decompo-
sition of the binary compounds, by undecom-
pounded bodies, can require no illustration. Pot-
assium separates chlorine and oxygene from all
Jknown bodies ; usually it produces potassa, but
sometimes by acting on compounds containing
abundance of oxygene, it forms the peroxide of
potassium. Carbon, in reducing metallic oxides,
forms either carbonic acid, or gaseous oxide of
carbon, according as the oxygene is more or
less strongly attracted by the basis^ When
oxides are decomposed by sulphur, sulphu-
reous gas, and sulphurets are almost always
formed.

7. Some of the instances which were formerly
supposed instances of single attractions are
now known to be connected with double attrac-
tions. This is remarkably the case in the pro-
duction of potassium by iron. The wiiter in the
hydrat of potassa, and the potassa seem to be

C 499 3

decomposed at the same time ; the Iron unites to
the oxygene of both ; the hydrogene and potassa
eorabine ; and their gaseous compound deposits
potassium on cooling.

IV. On ihe Methods of separating the undecomposed
Bodies from each other,

1. General methods of separating the unde-
corapounded bodies from each other may be
learnt from a consideration of the processes by
which they are procured; but there are other
modes which apply to many of their compounds,
and which are still more simple.

2. As all the undecomposed bodies differ in
the manner in which they are affected by heat,
many of them may be separated from com-
pounds, by exposing them to different tem-
peratures. Thus oxygencj chlorine, mercury,
phosphorus, and sulphur may be detached from
many bodies by the process of ignition.

3. In most cases, however, complicated me-
thods are necessary, particularly in cases when
the bodies 'are united to oxygene and acids or
to chlorine; the compounds of chlorine differ
very much in volatility, and in cases when they
are mixed together, they appear to act upon
each other with very little energy only : hence,
if it is possible to combine all the elements of a
compound with chlorine, by the action of th«

t 500 ]

gas, or of muriatic acid, or nitro-muriatic acid,
they may be easily separated by the application
of a heat gradually increased. Amongst the
metallic combinations, that of tin when saturated
with chlorine rises first, then those of arsenic,
antimony, tellurium, iron, zinc, bismuth, in the
order in which they have been named.

Silver is easily separated from solutions in
which it exists by muriatic acid, with the chlo-
rine of which it forms an insoluble compound;
and in the same way chlorine is separated, and
its quantity in any substance ascertained by
means of solution of silver.

Oxide of iron is separated from solutions by
succinate of ammonia, with which it forms an
insoluble salt. The oxides of copper, nickel, and
cobalt, are all soluble in ammonia. Those of
zinc, tellurium, tin, and platinum, in solution of
potassa. Acids are separated by alkalies ; and
alumina, silica, zircona, ittria, glucina, and the
alkaline earths, may with facility be detached
from their combinations by the action of acids,
alkalies, and carbonates. Oxide of lead and
baryta may be easily separated from other
bodies, in consequence of their forming inso-
ble compounds with sulphuric acid.

4. The order in which metals precipitate each
other from solutions, is nearly in the ratio of
their attraction for oxygene ; and in all cases of

lielitral Compounds, the precipitating metal takes
the oxygene and acid of the metal thrown
down. Iron readily precipitates copper ; — zinc
readily throws down tin, lead, tellurium^ bis-
muth, 8cc. and in general the metallic substances,
as has been stated page 14 8, attract oxygene, and
^tecipitate each other in a ratio connected with
their electrical relations ; those that are positive
with respect to others having the highest attrac-
tive powers for oxygene and acids.

By Voltaic electricity all substances are sepa-
rated from their compounds with oxygene and
chlorine; or alkalies, earths, and oxides are
separated from acids ; as has been mentioned
page 161, and that in an uniform order and in
definite proportions, so that Voltaic electricity
offers general methods of decomposing all com-
pounds soluble in water ; and for most experi-
ments of this kind very small combinations only
are necessary : if small quantities of the materials
are employed, two or three double plates are
sufficient for decomposing most metallic solu-
tions. The energies of small powers in acting
upon bodies by diminishing the quantities ex.
posed to their agency, has been happily shewn
by Dr. Wollaston, in the decomposition of
water by a common small electrical machine,
hy passing the electricity from surfaces of about
^^^ncsVo square inch ; and the same philo-

[ 502 ]

sopher has produced the ignition of platinum
in leaf of -j—^ of an inch in thickness, by a
single, series of double metals of a few inches
square: the zinc is circular, forming a small
hollow tube, and surrounded by copper opposed
to each side of it, and bent so as to correspond
to the form ol the zinc ; when the two metals are
exposed to the action of an acid, and connected
by the leaf of platinum, the effect is produced.

V. General Observalions, and Conclusion of Pari

First.

1. Few of the undecompounded bodies, or even
of the primary compounds, as is evident from
what has been said, are found in an uncombined
stale on our globe ; their tendency to unite with
each other is constantly exerted; and a series
of decompositions and recombinations are con-
stantly occurring in the phenomena of nature,
and in the operations of art. The compounds
containing more than two elements, will form
the subjects of consideration for the second
part of this work, and their arrangements in
the mineral, vegetable, and animal kingdoms ^
when the principles that have been advanced
in the preceding pages, will be applied to the
elucidation of an important series of changes
belonging to inorganic and to organic matter.
As far as our investigations have extended, the

[ 503 ]

same elements belong to the same parts of the
system. The composition of the atmosphere
and the ocean are analogous, as far as the heights
of one, and the depths of the other have been
examined. The matters thrown out by volcanoes
are earthy or stony aggrep;ates, and they may
owe their origin to the action of air and water
upon the metallic bases of the earths and alka-
lies ; an action which may be supposed to be
connected with the production of subterraneous
fires. Even the substances that fall from meteors,
though differing in their form and appearance
from any of the bodies belonging to our earth,
yet contain well known elements, silica, mag-
nesia, sulphur, and the two magnetic metals,
iron and nickel.

5. A few undecompounded bodies, which may
perhaps ultimately be resolved into still fewer
elements, or which may be different forms of
the same material, constitute the whole of our
tangible universe of things. By experiment
they are discovered, even in the most compli-
cated arrangements ; and experiment is as it were
the chain that binds down the Proteus of nature,
and obliges it to confess its real form and divine
origin.

The laws which govern the pha?nomena of
chemistry, produce invariable results ; which
may be made the guide of operations in the arts ;

1

[ 504 ]

and \vhich ins^ure the uniforniity of the systens"
of nature, the arrangements of which are
marked by creative intelligence, and made con-
stantly subservient to the production of life,
and the increa&e of happiness.

London : Printed by W. Bulmcrand Co.
Clc* eland-row, St. James's.

[ 505 ]

On the Mode of calculating the JYumbers repre*
senting the Elements.

Note referring to page 107-

The smallest quantity bearing a definite rela
tion to another quantity or quantities, is always
the datura, whether it is the first, second, third,
fourth, or any other added quantity in the
Combination. Potassium forms two combinations
with oxygene ; page 323, 1»0 of potassium in
weight unite to 20,1 of oxygene to form pure
potassa, and to 57 8 to form the orange oxide of
potassium. 20.1, the smallest number is taken,
and as 20.1: 100:: 15, the number representing
oxygene to 74.99; or adding the minute frac-
tional part to 75 ; and 57-8 is nearly 3 times 20 :
and the difference may be easily explained by
supposing that in experiments on the peroxide,
it is scarcely possible to convert the whole of
the metal into potassium.

To give another instance in which the datum
is taken from the peroxide: The peroxide of
lead contains from 3 to 3,5 per cent, more oxy-
gene, than minium ; and the first oxide known,
Massicot, consists of about 100 of lead to 7.52
of oxygene ; minium of J 00 to between 10 and
12; and llie puce coloured oxide of 100 of
metal to about 15 ; and the smallest proportion
amongst these is 3.76 of oxygene, and 3.76:
100:: 15 is to 39s, the number representing lead;
and massicot is supposed to contain twice this
quantity of oxygene, 398: 50 : : 100 is to 7.53.
VOL. I. L i

APPENDIX.

Since the last sheet has been sent to the press,
M. Berzelius has had the goodness to commu-
nicate to me the following estimates, some of
■which agree very nearly with those given in
the preceding pages ; others are new, and all
afford evidences of the truth of the theory of
definite proportions. It is peculiarly satis-
factory to me, to be able to state the coincidence
of so many of the conclusions of this distin-
guished chemist with my own results, obtained
usually by very different methods of operation.

Of the Oxides of Antimony.

Metal. Oxygene. Metal.

First Oxide 100 4,65 96,826

Second — 18,6 84,817

Third — 27,9 78,19

Fourth — 37,2 72,85

Oxygene.
3,174^4
15,683
21,81
27,15

The Sulphwet of Antimony, is composed of 100 parts
of Metal, and of 37,25 parts of Sulphur.

Oxides of Tin.
Metal. Oxygene. Metal.
First Oxide 100 13,6 88,03
Second — 20,4 83,13

Third — 27,2 78,61

The Sulphurets of Tin,

Metal. Oxygene. Metal.

First 100 27,234 78,6

Second — 40,851 71,8

Third — 54,468

Oxygene.
11,97 1
16,87
21,39 .

If

Oxygene.
21,4
28,2

The Oxide of Tellurium,
100 parts of Metal, with 24,83 parts of Oxygene,

Telluretted Hydrogene,
Tellurium 100 parts. Hydrogene 1,948.

APPENDI5C.

First
Second

First
Second

The Oxides of Gold.

Metal. Oxygene. Metal.
100 11,026 96,13
12,077 89,225

The Oxides of Platinum.

Metal. Oxygeae. Metal.
100 8,287 92,35
— 16,574 85,9

Oxygene.
3,87 jl
10,775 i 3

Oxygene.
7,65
14,1

) 2

First

Second

Third

Fourth

Fifth

The Oxide qf Palladium.
Metal 100. Oxygene 14,055

Sulphuret of Palladium.
Metal 100. Sulphur 28,15.

The Oxides of Manganesum.
Oxygene

Metal.
100

7,0266
14,0533

28,1077

42,16

56,215

Metal.
93,435
87,68
78,1
72,25
64

Oxygene.
6,565-^

2
•4

27,75 Is

36 J 8

12,32 i
21,9

Metallic Oxides examined by other Swedish Chemists*

Oxides of Mercury, bvM. Sefstrom.
First, Metal 100. Oxygene 3,95 7 1

Second, 100.

7,9

. Oxide of Bismuth, by M. de Lagerhielm.
Metal 100. Oxygene 11,275.

Oxide of Nickel, by M. de RolholF.
First, Metal 100. Oxygene 27,3 7 1

il^

Second,

40,95

Oxide of Cobalt, by the same.

First, Metal 100. Oxygene 27,3
Second, . — 40,95

Oxide of Cerium, by M. de Hisinger.

First, Metal 100. Oxygene i 7,41 7 1
Second, . — ■■ 26, 1 1 5 i If

rUite I .

J.ou-rv Sadp!

Piih^June j^hSj'j. bvXJohiu-on.^CSSraiiLr Church. YMondon.

Plate II.

' Zo^v}y Sculp*.

Piiblf Jiuiei-^}i8v2. by J Johnson, &r C^S^hutU QmrchJ'^lQndon.

riate IF.

I

mtc. r.

Tiff. 26.

9

Zowry soiip.

1

9

i

1

[ 507 ]

To face Plate VII.

Plate VII. Fig. 27, represents a furnace for
the general purposes of experiments. The
upper part of the furnace is a sand batli; The
lower part may be employed for fusion or
distillation, or for igniting tubes. It may be
used in any room where there is a flue, and it
serves the purpose of a stove.

Plate VIII. Fig. 28, represents the mercurial
apparatus. The tube in the frame represents
the apparatus for detonating mixtures of gasses i
it is connected with a spiral spring.

Fig. 30, represents another apparatus for
detonation.

[ 509 1

1

To face Plate IX.

The opposite Plate represents an apparatus
for minute experiments ; the instruments are
delineated of their real siie. The cups should
should be of platinum, the tubes and small
retorts of glass ; the blow pipe may be of
silver, with an extremity of platinum. By the
help of these instruments, and a little wooden
trough holding a few pounds of mercury, an
electrophorus for giving a spark to act upon
mixtures of gasses, or compound gasses ; and
a few bottles containing acids, alkalies, and pre-
cipitants, a number of useful experiments may
be made. Boxes containing the apparatus on
a very small scale, are neatly made, and sold at
reasonable prices, by Mr. Newman, 10, Old
Lisle-street, London.

London : Printed by W.'Bulmcr and Co,
CUvelaiui •roWj St, Janies's*

To face Plate X.

TflE opposite Plate represents a Gasometer,
fey which a stream of oxygene gas may be
thrown upon ignited charcoal, for the purpose
of fusing or burning bodies, Sec,

1-

the same Author ,

tn ihe year 1800 were published, in one Volume 8vo.
price 10s. 6d. in boards.

Researches, Chemical and Philosophical,
chiefly concerning Nitrous Oxide, or Dephlogisticated
Nitrous Air, and its Respiration.

I